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| Delaware                                  |   | 75-2310852          |
|-------------------------------------------|--------|---------------------|
| (State or other jurisdiction              |   | (I.R.S. Employer    |
| of incorporation or organization)         |   | Identification No.) |
|                                      |   |                |
| 6 Desta Drive, Suite 6500, Midland, Texas |   | 79705               |
| (Address of principal executive office)   |   | (Zip Code)          |

| Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.                                                                                                                                                                                                                                    |  ̈ Yes | x No      |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------|-----------|
|                                                                                                                                                                                                                                                                                                                                                       |       |      |
| Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.                                                                                                                                                                                                                               |  ̈ Yes | x No      |
|                                                                                                                                                                                                                                                                                                                                                       |       |      |
| Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.   | x Yes      |  ̈ No |
|                                                                                                                                                                                                                                                                                                                                                       |       |      |
| Indicate by check mark whether the registrant has submitted electronically and posted on its corporate website, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files). |  ̈ Yes |  ̈ No |

| Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant's knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K.x |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, or a non-accelerated filer.  See definition of “accelerated filer and large accelerated filer” in Rule 12b-2 of the Exchange Act. |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Large accelerated filer  ̈                                                                                                                                                                                                                            |   | Accelerated filer  ̈ |   | Non-accelerated filer  x |   | Smaller reporting company ̈ |   |

| Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act). |  ̈ Yes | x No |
|---------------------------------------------------------------------------------------------------------|------------|------|

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|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | Page   |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|
| Part I                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Item 1.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | Business                                                                                                                                                    | 3      |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Item 1A.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Risk Factors                                                                                                                                                | 7      |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Item 1B.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Unresolved Staff Comments                                                                                                                                   | 10     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Item 2.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | Properties                                                                                                                                                  | 10     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Item 3.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | Legal Proceedings                                                                                                                                           | 11     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Item 4.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | (Removed and Reserved)                                                                                                                                      | 11     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Part II                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Item 5.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | Market for Registrant's Common Equity, Related                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      | Stockholder Matters and Issuer Purchases of Equity Securities                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    | 12     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Item 6.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | Selected Financial Data                                                                                                                                     | 13     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Item 7.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | Management's Discussion and Analysis of                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      | Financial Condition and Results of Operations                                                                                                                                   | 14     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Item 7A.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Quantitative and Qualitative Disclosures About Market Risk                                                                                                  | 16     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Item 8.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | Financial Statements and Supplementary Data                                                                                                                 | 17     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Item 9.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | Changes in and Disagreements with Accountants                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      | on Accounting and Financial Disclosure                                                                                                                                          | 30     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Item 9A.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Controls and Procedures                                                                                                                                     | 30     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Item 9B.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Other Information                                                                                                                                           | 31     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Part III                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Item 10.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Directors, Executive Officers and Corporate Governance                                                                                                      | 32     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Item 11.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Executive Compensation                                                                                                                                      | 32     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Item 12.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Security Ownership of Certain Beneficial Owners and Management and                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      | Related Stockholder Matters                                                                                                                                                     | 33     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Item 13.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Certain Relationships and Related Transactions, and Director Independence                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        | 33     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Item 14.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Principal Accounting Fees and Services                                                                                                                      | 33     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Part IV                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Item 15.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Exhibits and Financial Statement Schedules                                                                                                                  | 34     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Glossary of Oil and Gas Terms                                                                                                                   | 35                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |
| Signatures                                                                                                                                      | 37                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |

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| ·   | amends the definition of proved reserves to require the use of average commodity prices based upon the prior 12 month period rather than year-end prices; |
|--------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|

| ·   | expands the type of technologies available to establish reserve estimates and categories; |
|--------------------|-------------------------------------------------------------------------------------------|

| ·   | modifies certain definitions used in estimating proved reserves; |
|--------------------|------------------------------------------------------------------|

| ·   | permits disclosure of probable and possible reserves; and |
|--------------------|-----------------------------------------------------------|

| ·   | permits disclosure of reserves based on different price and cost criteria, such as futures prices or management forecasts. |
|--------------------|----------------------------------------------------------------------------------------------------------------------------|

|                               |   | Proved Developed |   |   | Proved       |   |   | Total       |   |
|------------------------------------|--------|------------------|--------|--------|--------------|--------|--------|-------------|--------|
|                               |   | Producing        |   |   | Nonproducing |   |   | Undeveloped |   |   | Proved |   |
| Oil (Bbls)                         |   |             | 77,000 |   |         |   | -      |        |   |   | - |   |   |   | 77,000 |   |
| Gas (Mcf)                          |   |             | 74,000 |   |         |   | -      |        |   |   | - |   |   |   | 74,000 |   |
| Total (BOE)                        |   |             | 89,000 |   |         |   | -      |        |   |   | - |   |   |   | 89,000 |   |
|                               |   |             |   |   |         |   |   |        |   |   |   |   |   |   |   |   |
| Standardized measure of discounted |   |             |   |   |         |   |   |        |   |   |   |   |   |   |   |   |
| future net cash flows              |   |             |   |   |         |   |   |        |   |   |   |   |   | $ | 1,469,000 |   |

|            |   | Proved Reserves |   |   |   |   |
|-----------------|--------|-----------------|--------|--------|--------|--------|
|            |   |            |   |   |   |   |   | Total Oil |   |   | Percent of |   |
|            |   | Oil             |   |   | Gas    |   |   | Equivalent |   |   | Total Oil |   |
|            |   | (Bbls)          |   |   | (Mcf)  |   |   | (BOE) |   |   | Equivalent |   |
| Slaughter       |   |            | 40,000 |   |   |   | - |   |   |   | 40,000 |   |   |   | 45.0 | % |
| Hackberry Yates |   |            | 10,000 |   |   |   | - |   |   |   | 10,000 |   |   |   | 11.2 | % |
| Jalmat          |   |            | 6,000  |   |   |   | 20,000 |   |   |   | 9,000 |   |   |   | 10.1 | % |
| Other           |   |            | 21,000 |   |   |   | 54,000 |   |   |   | 30,000 |   |   |   | 33.7 | % |
| Total           |   |            | 77,000 |   |   |   | 74,000 |   |   |   | 89,000 |   |   |   | 100.0 | % |

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Item 

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| Item 5. | Market for Registrant's Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities |
|---------|--------------------------------------------------------------------------------------------------------------|

|           |   | Total Number |   |   |          |   |
|----------------|--------|--------------|--------|--------|---------------|--------|
|           |   | of Units     |   |   | Average Price |   |
| Period         |   | Purchased    |   |   | Paid Per Unit |   |
| January 2010   |   |         | -      |   |          | $      | - |   |
| February 2010  |   |         | -      |   |          |   | - |   |
| March 2010     |   |         | -      |   |          |   | - |   |
| April 2010     |   |         | -      |   |          |   | - |   |
| May 2010       |   |         | -      |   |          |   | - |   |
| June 2010      |   |         | 10.0   |   |          |   | 7.32 |   |
| July 2010      |   |         | -      |   |          |   | - |   |
| August 2010    |   |         | -      |   |          |   | - |   |
| September 2010 |   |         | 182.0  |   |          |   | 4.42 |   |
| October 2010   |   |         | -      |   |          |   | - |   |
| November 2010  |   |         | -      |   |          |   | - |   |
| December 2010  |   |         | -      |   |          |   | - |   |
| TOTALS         |   |         | 192.0  |   |          | $      | 4.57 |   |

----

Data

|                                  |   | Years ended December 31, |     |
|---------------------------------------|--------|--------------------------|----------|
|                                  |   | 2010                     |     |   | 2009 |   |   | 2008 |   |   | 2007 |   |   | 2006 |   |
| Revenues                              |   | $                        | 12,456   |   |   | $ | 243,412 |   |   | $ | 676,683 |   |   | $ | 424,116 |   |   | $ | 412,625 |   |
|                                  |   |                     |     |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Net (loss) income                     |   |                     | (140,753 | ) |   |   | 79,061 |   |   |   | 521,272 |   |   |   | 267,363 |   |   |   | 271,735 |   |
|                                  |   |                     |     |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Partners' share of net (loss) income: |   |                     |     |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
|                                  |   |                     |     |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| General partners                      |   |                     | (12,037  | ) |   |   | 10,661 |   |   |   | 54,432 |   |   |   | 28,886 |   |   |   | 28,688 |   |
|                                  |   |                     |     |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Limited partners                      |   |                     | (128,716 | ) |   |   | 68,400 |   |   |   | 466,840 |   |   |   | 238,477 |   |   |   | 243,047 |   |
|                                  |   |                     |     |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Limited partners'                     |   |                     |     |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Net (loss) income per unit            |   |                     | (11.37   | ) |   |   | 6.04 |   |   |   | 41.25 |   |   |   | 21.07 |   |   |   | 21.48 |   |
|                                  |   |                     |     |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Limited partners'                     |   |                     |     |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| cash distributions per unit           |   |                     | 2.40     |   |   |   | 4.15 |   |   |   | 53.05 |   |   |   | 18.33 |   |   |   | 26.35 |   |
|                                  |   |                     |     |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Total assets                          |   | $                        | 276,666  |   |   | $ | 384,909 |   |   | $ | 372,137 |   |   | $ | 471,343 |   |   | $ | 426,228 |   |

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|                                      |   | Year Ended December 31, |   |
|-------------------------------------------|--------|-------------------------|--------|
|                                      |   | 2010                    |   |   | 2009 |   |   | 2008 |   |
| Oil production in barrels                 |   |                    | 8,702  |   |   |   | 9,298 |   |   |   | 9,649 |   |
| Gas production in mcf                     |   |                    | 16,322 |   |   |   | 18,983 |   |   |   | 23,562 |   |
| Total (BOE)                               |   |                    | 11,422 |   |   |   | 12,462 |   |   |   | 13,576 |   |
| Average price per barrel of oil           |   | $                       | 74.57  |   |   | $ | 55.53 |   |   | $ | 96.74 |   |
| Average price per mcf of gas              |   | $                       | 5.32   |   |   | $ | 4.29 |   |   | $ | 9.69 |   |
| Partnership distributions                 |   | $                       | 30,216 |   |   | $ | 52,548 |   |   | $ | 667,414 |   |
| Limited partner distributions             |   | $                       | 27,163 |   |   | $ | 46,931 |   |   | $ | 600,318 |   |
| Per unit distribution to limited partners |   | $                       | 2.40   |   |   | $ | 4.15 |   |   | $ | 53.05 |   |
| Number of limited partner units           |   |                    | 11,316 |   |   |   | 11,316 |   |   |   | 11,316 |   |

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|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |   | Page   |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|--------|
| Report of Independent Registered Public Accounting Firm                                                                                                    |   | 18     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |   |   |
| Balance Sheets                                                                                                                                             |   | 19     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |   |   |
| Statements of Operations                                                                                                                                   |   | 20     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |   |   |
| Statements of Changes in Partners' (Deficit) Equity                                                                                                        |   | 21     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |   |   |
| Statements of Cash Flows                                                                                                                                   |   | 22     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |   |   |
| Notes to Financial Statements                                                                                                                              |   | 23     |

----

Report 

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Southwest 

|                                       |   | December 31, |      |
|--------------------------------------------|--------|--------------|-----------|
|                                       |   | 2010         |      |   | 2009 |   |
|                                       |   |         |      |   |   |   |
| Assets                                     |   |         |      |   |   |   |
|                                       |   |         |      |   |   |   |
| Current assets:                            |   |         |      |   |   |   |
| Cash and cash equivalents                  |   | $            | 2,268     |   |   | $ | 46,268 |   |
| Receivable from Managing General Partner   |   |         | -         |   |   |   | 46,837 |   |
| New Mexico income tax deposits             |   |         | 12,280    |   |   |   | 9,306 |   |
|                                       |   |         |      |   |   |   |   |   |
| Total current assets                       |   |         | 14,548    |   |   |   | 102,411 |   |
|                                       |   |         |      |   |   |   |   |   |
| Oil and gas properties - using the full-   |   |         |      |   |   |   |   |   |
| cost method of accounting                  |   |         | 4,390,708 |   |   |   | 4,390,708 |   |
| Less accumulated depreciation,             |   |         |      |   |   |   |   |   |
| depletion and amortization                 |   |         | 4,128,590 |   |   |   | 4,108,210 |   |
|                                       |   |         |      |   |   |   |   |   |
| Net oil and gas properties                 |   |         | 262,118   |   |   |   | 282,498 |   |
|                                       |   |         |      |   |   |   |   |   |
|                                       |   | $            | 276,666   |   |   | $ | 384,909 |   |
|                                       |   |         |      |   |   |   |   |   |
| Liabilities and Partners' (Deficit) Equity |   |         |      |   |   |   |   |   |
|                                       |   |         |      |   |   |   |   |   |
| Current liability:                         |   |         |      |   |   |   |   |   |
| Payable to Managing General Partner        |   | $            | 101,363   |   |   | $ | - |   |
|                                       |   |         |      |   |   |   |   |   |
| Asset retirement obligation                |   |         | 242,631   |   |   |   | 281,268 |   |
|                                       |   |         |      |   |   |   |   |   |
| Partners' (deficit) equity:                |   |         |      |   |   |   |   |   |
| General Partner                            |   |         | (25,127   | ) |   |   | (10,037 | ) |
| Limited partners                           |   |         | (42,201   | ) |   |   | 113,678 |   |
|                                       |   |         |      |   |   |   |   |   |
| Total partners' (deficit) equity           |   |         | (67,328   | ) |   |   | 103,641 |   |
|                                       |   |         |      |   |   |   |   |   |
|                                       |   | $            | 276,666   |   |   | $ | 384,909 |   |

----

Southwest 

|                                     |   | Years ended December 31, |     |
|------------------------------------------|--------|--------------------------|----------|
|                                     |   | 2010                     |     |   | 2009 |   |   | 2008 |   |
| Revenues                                 |   |                     |     |   |   |   |   |   |   |
|                                     |   |                     |     |   |   |   |   |   |   |
| Income from net profits interests        |   | $                        | 12,376   |   |   | $ | 243,365 |   |   | $ | 676,060 |   |
| Interest income                          |   |                     | 80       |   |   |   | 41 |   |   |   | 615 |   |
| Other                                    |   |                     | -        |   |   |   | 6 |   |   |   | 8 |   |
|                                     |   |                     | 12,456   |   |   |   | 243,412 |   |   |   | 676,683 |   |
|                                     |   |                     |     |   |   |   |   |   |   |   |   |   |
| Expenses                                 |   |                     |     |   |   |   |   |   |   |   |   |   |
|                                     |   |                     |     |   |   |   |   |   |   |   |   |   |
| Depreciation, depletion and amortization |   |                     | 20,381   |   |   |   | 27,551 |   |   |   | 23,044 |   |
| Accretion expense                        |   |                     | 19,668   |   |   |   | 23,640 |   |   |   | 19,207 |   |
| General and administrative               |   |                     | 113,160  |   |   |   | 113,160 |   |   |   | 113,160 |   |
|                                     |   |                     | 153,209  |   |   |   | 164,351 |   |   |   | 155,411 |   |
|                                     |   |                     |     |   |   |   |   |   |   |   |   |   |
| Net (loss) income                        |   | $                        | (140,753 | ) |   | $ | 79,061 |   |   | $ | 521,272 |   |
|                                     |   |                     |     |   |   |   |   |   |   |   |   |   |
| Net (loss) income allocated to:          |   |                     |     |   |   |   |   |   |   |   |   |   |
|                                     |   |                     |     |   |   |   |   |   |   |   |   |   |
| Managing General Partner                 |   | $                        | (10,833  | ) |   | $ | 9,595 |   |   | $ | 48,989 |   |
|                                     |   |                     |     |   |   |   |   |   |   |   |   |   |
| General Partner                          |   | $                        | (1,204   | ) |   | $ | 1,066 |   |   | $ | 5,443 |   |
|                                     |   |                     |     |   |   |   |   |   |   |   |   |   |
| Limited partners                         |   | $                        | (128,716 | ) |   | $ | 68,400 |   |   | $ | 466,840 |   |
|                                     |   |                     |     |   |   |   |   |   |   |   |   |   |
| Per limited partner unit                 |   | $                        | (11.37   | ) |   | $ | 6.04 |   |   | $ | 41.25 |   |

----

Southwest 

|                         |   | General  |    |   | Limited  |   |     |   |   |
|------------------------------|--------|----------|---------|--------|----------|--------|----------|--------|--------|
|                         |   | Partners |    |   | Partners |   |     | Total  |   |
| Balance at December 31, 2007 |   | $        | (2,417  | )      |     | $      | 225,687  |   |   | $ | 223,270 |   |
|                         |   |     |    |   |     |   |     |   |   |   |   |   |
| Net income                   |   |     | 54,432  |   |     |   | 466,840  |   |   |   | 521,272 |   |
|                         |   |     |    |   |     |   |     |   |   |   |   |   |
| Distributions                |   |     | (67,096 | )      |     |   | (600,318 | )      |   |   | (667,414 | ) |
|                         |   |     |    |   |     |   |     |   |   |   |   |   |
| Balance at December 31, 2008 |   |     | (15,081 | )      |     |   | 92,209   |   |   |   | 77,128 |   |
|                         |   |     |    |   |     |   |     |   |   |   |   |   |
| Net income                   |   |     | 10,661  |   |     |   | 68,400   |   |   |   | 79,061 |   |
|                         |   |     |    |   |     |   |     |   |   |   |   |   |
| Distributions                |   |     | (5,617  | )      |     |   | (46,931  | )      |   |   | (52,548 | ) |
|                         |   |     |    |   |     |   |     |   |   |   |   |   |
| Balance at December 31, 2009 |   |     | (10,037 | )      |     |   | 113,678  |   |   |   | 103,641 |   |
|                         |   |     |    |   |     |   |     |   |   |   |   |   |
| Net loss                     |   |     | (12,037 | )      |     |   | (128,716 | )      |   |   | (140,753 | ) |
|                         |   |     |    |   |     |   |     |   |   |   |   |   |
| Distributions                |   |     | (3,053  | )      |     |   | (27,163  | )      |   |   | (30,216 | ) |
|                         |   |     |    |   |     |   |     |   |   |   |   |   |
| Balance at December 31, 2010 |   | $        | (25,127 | )      |     | $      | (42,201  | )      |   | $ | (67,328 | ) |

----

Southwest 

|                                                 |   | Years ended December 31, |     |
|------------------------------------------------------|--------|--------------------------|----------|
|                                                 |   | 2010                     |     |   | 2009 |   |   | 2008 |   |
| Cash flows from operating activities:                |   |                     |     |   |   |   |   |   |   |
| Cash received from income from net profits interests |   | $                        | 99,297   |   |   | $ | 200,906 |   |   | $ | 743,227 |   |
| Cash paid to suppliers                               |   |                     | (113,160 | ) |   |   | (151,452 | ) |   |   | (74,868 | ) |
| Interest received                                    |   |                     | 80       |   |   |   | 41 |   |   |   | 615 |   |
| Other                                                |   |                     | -        |   |   |   | 6 |   |   |   | 8 |   |
|                                                 |   |                     |     |   |   |   |   |   |   |   |   |   |
| Net cash (used in) provided by operating activities  |   |                     | (13,783  | ) |   |   | 49,501 |   |   |   | 668,982 |   |
|                                                 |   |                     |     |   |   |   |   |   |   |   |   |   |
| Cash flows used in financing activities:             |   |                     |     |   |   |   |   |   |   |   |   |   |
| Distributions to partners                            |   |                     | (30,216  | ) |   |   | (52,548 | ) |   |   | (667,414 | ) |
|                                                 |   |                     |     |   |   |   |   |   |   |   |   |   |
| Net (decrease) increase in cash and cash equivalents |   |                     | (43,999  | ) |   |   | (3,047 | ) |   |   | 1,568 |   |
|                                                 |   |                     |     |   |   |   |   |   |   |   |   |   |
| Beginning of year                                    |   |                     | 46,268   |   |   |   | 49,315 |   |   |   | 47,747 |   |
|                                                 |   |                     |     |   |   |   |   |   |   |   |   |   |
| End of year                                          |   | $                        | 2,269    |   |   | $ | 46,268 |   |   | $ | 49,315 |   |
|                                                 |   |                     |     |   |   |   |   |   |   |   |   |   |
| Reconciliation of net (loss) income to net cash      |   |                     |     |   |   |   |   |   |   |   |   |   |
| provided by operating activities:                    |   |                     |     |   |   |   |   |   |   |   |   |   |
|                                                 |   |                     |     |   |   |   |   |   |   |   |   |   |
| Net (loss) income                                    |   | $                        | (140,753 | ) |   | $ | 79,061 |   |   | $ | 521,272 |   |
|                                                 |   |                     |     |   |   |   |   |   |   |   |   |   |
| Adjustments to reconcile net (loss) income to        |   |                     |     |   |   |   |   |   |   |   |   |   |
| net cash provided by operating activities:           |   |                     |     |   |   |   |   |   |   |   |   |   |
|                                                 |   |                     |     |   |   |   |   |   |   |   |   |   |
| Depreciation, depletion and amortization             |   |                     | 20,381   |   |   |   | 27,551 |   |   |   | 23,044 |   |
| Accretion expense                                    |   |                     | 19,668   |   |   |   | 23,640 |   |   |   | 19,207 |   |
| Settlement of asset retirement obligations           |   |                     |     |   |   |   |   |   |   |   |   |   |
| for plugged and abandoned wells                      |   |                     | (58,305  | ) |   |   | (5,401 | ) |   |   | (18,078 | ) |
| Decrease (increase) in receivables and deposits      |   |                     | 43,863   |   |   |   | (37,058 | ) |   |   | 85,245 |   |
| Increase (decrease) in payables                      |   |                     | 101,363  |   |   |   | (38,292 | ) |   |   | 38,292 |   |
|                                                 |   |                     |     |   |   |   |   |   |   |   |   |   |
| Net cash provided by operating activities            |   | $                        | (13,783  | ) |   | $ | 49,501 |   |   | $ | 668,982 |   |
|                                                 |   |                     |     |   |   |   |   |   |   |   |   |   |
| Noncash investing and financing activities:          |   |                     |     |   |   |   |   |   |   |   |   |   |
| Increase in oil and gas properties –           |   |                     |     |   |   |   |   |   |   |   |   |   |
| Asset retirement obligations                         |   | $                        | -        |   |   | $ | 6,312 |   |   | $ | 7,515 |   |

----

Southwest 

| 1. | Organization |
|----|--------------|

|                                      | Limited  |   | General  |
|-------------------------------------------|----------|--------|----------|
|                                      | Partners |   | Partners |
| Interest income on capital contributions  | 100%     |   | -        |
| Oil and gas sales                         | 90%      |   | 10%      |
| All other revenues                        | 90%      |   | 10%      |
| Organization and offering costs (1)       | 100%     |   | -        |
| Amortization or organization costs        | 100%     |   | -        |
| Property acquisition costs                | 100%     |   | -        |
| Gain/loss on property disposition         | 90%      |   | 10%      |
| Operating and administrative costs (2)    | 90%      |   | 10%      |
| Depreciation, depletion, and amortization |     |   |     |
|  of oil and gas properties           | 100%     |   | -        |
| All other costs                           | 90%      |   | 10%      |

|   | (1) | All organization costs in excess of 3% of initial capital contributions will be paid by the Managing General Partner and will be treated as a capital contribution.  The Partnership paid the Managing General Partner an amount equal to 3% of initial capital contributions for such organization costs. |
|--------|-----|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|   | (2) | Administrative costs in any year, which exceed 2% of capital contributions shall be paid by the Managing General Partner and will be treated as a capital contribution. |
|--------|-----|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 2. | Summary of Significant Accounting Policies |
|----|--------------------------------------------|

----

| 2. | Summary of Significant Accounting Policies - continued |
|----|--------------------------------------------------------|

----

| 2. | Summary of Significant Accounting Policies - continued |
|----|--------------------------------------------------------|

|                                                        |   | 2010   |    |   | 2009   |   |
|-------------------------------------------------------------|--------|--------|---------|--------|--------|--------|
| Beginning of year                                           |   | $      | 281,268 |   |   | $      | 256,717 |   |
| Reduction of obligations due to wells plugged and abandoned |   |   | (58,305 | )      |   |   | (5,401 | ) |
| Accretion expense                                           |   |   | 19,668  |   |   |   | 23,640 |   |
| Revisions of previous estimates                             |   |   | -       |   |   |   | 6,312 |   |
| End of year                                                 |   | $      | 242,631 |   |   | $      | 281,268 |   |

----

| 5. | Related Party Transactions |
|----|----------------------------|

----

| 6. | Oil and Gas Reserves Information (unaudited) |
|----|----------------------------------------------|

| ·   | amends the definition of proved reserves to require the use of average commodity prices based upon the prior 12-month period rather than year-end prices; |
|--------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|

| ·   | expands the type of technologies available to establish reserve estimates and categories; |
|--------------------|-------------------------------------------------------------------------------------------|

| ·   | modifies certain definitions used in estimating proved reserves; |
|--------------------|------------------------------------------------------------------|

| ·   | permits disclosure of probable and possible reserves; and |
|--------------------|-----------------------------------------------------------|

| ·   | permits disclosure of reserves based on different price and cost criteria, such as futures prices or management forecasts. |
|--------------------|----------------------------------------------------------------------------------------------------------------------------|

|                            |   | Oil (bbls) |    |   | Gas (mcf) |   |
|---------------------------------|--------|------------|---------|--------|-----------|--------|
| Total Proved -                  |   |       |    |   |      |   |
| January 1, 2008                 |   |       | 111,000 |   |      |   | 188,000 |   |
|                            |   |       |    |   |      |   |   |   |
| Revisions of previous estimates |   |       | (38,000 | )      |      |   | (46,000 | ) |
| Production                      |   |       | (10,000 | )      |      |   | (24,000 | ) |
| December 31, 2008               |   |       | 63,000  |   |      |   | 118,000 |   |
|                            |   |       |    |   |      |   |   |   |
| Revisions of previous estimates |   |       | 28,000  |   |      |   | (6,000 | ) |
| Production                      |   |       | (9,000  | )      |      |   | (19,000 | ) |
| December 31, 2009               |   |       | 82,000  |   |      |   | 93,000 |   |
|                            |   |       |    |   |      |   |   |   |
| Revisions of previous estimates |   |       | 4,000   |   |      |   | (3,000 | ) |
| Production                      |   |       | (9,000  | )      |      |   | (16,000 | ) |
| December 31, 2010               |   |       | 77,000  |   |      |   | 74,000 |   |
|                            |   |       |    |   |      |   |   |   |
| Proved developed reserves -     |   |       |    |   |      |   |   |   |
|                            |   |       |    |   |      |   |   |   |
| December 31, 2008               |   |       | 63,000  |   |      |   | 117,000 |   |
| December 31, 2009               |   |       | 82,000  |   |      |   | 93,000 |   |
| December 31, 2010               |   |       | 77,000  |   |      |   | 74,000 |   |
|                            |   |       |    |   |      |   |   |   |

----

| 6. | Oil and Gas Reserves Information (unaudited) - continued |
|----|----------------------------------------------------------|

----

| 6. | Oil and Gas Reserves Information (unaudited) - continued |
|----|----------------------------------------------------------|

|                                          |   | 2010   |      |   | 2009   |   |      | 2008   |   |
|-----------------------------------------------|--------|--------|-----------|--------|--------|--------|-----------|--------|--------|
| Future cash inflows                           |   | $      | 5,850,000 |   |   | $      | 4,733,000 |   |   | $ | 3,433,000 |   |
| Production, development and abandonment costs |   |   | 3,378,000 |   |   |   | 2,763,000 |   |   |   | 1,815,000 |   |
| Future net cash flows                         |   |   | 2,472,000 |   |   |   | 1,970,000 |   |   |   | 1,618,000 |   |
| 10% annual discount for                       |   |   |      |   |   |   |      |   |   |   |   |   |
| estimated timing of cash flows                |   |   | 1,003,000 |   |   |   | 856,000   |   |   |   | 681,000 |   |
| Standardized measure of                       |   |   |      |   |   |   |      |   |   |   |   |   |
| discounted future net cash flows              |   | $      | 1,469,000 |   |   | $      | 1,114,000 |   |   | $ | 937,000 |   |

|                                                   |   | 2010   |      |   | 2009   |   |      | 2008   |   |
|--------------------------------------------------------|--------|--------|-----------|--------|--------|--------|-----------|--------|--------|
| Sales of oil and gas produced, net of production costs |   | $      | (12,000   | )      |   | $      | (243,000  | )      |   | $ | (676,000 | ) |
| Changes in prices and production costs                 |   |   | 254,000   |   |   |   | 28,000    |   |   |   | (1,839,000 | ) |
| Changes of production rates (timing) and others        |   |   | (56,000   | )      |   |   | (11,000   | )      |   |   | 203,000 |   |
| Revisions of previous quantities estimates             |   |   | 58,000    |   |   |   | 309,000   |   |   |   | (518,000 | ) |
| Accretion of discount                                  |   |   | 111,000   |   |   |   | 94,000    |   |   |   | 342,000 |   |
| Discounted future net cash flows -                     |   |   |      |   |   |   |      |   |   |   |   |   |
| Beginning of year                                      |   |   | 1,114,000 |   |   |   | 937,000   |   |   |   | 3,425,000 |   |
| End of year                                            |   | $      | 1,469,000 |   |   | $      | 1,114,000 |   |   | $ | 937,000 |   |

| 7. | Selected Quarterly Financial Results – (unaudited) |
|----|----------------------------------------------------------|

|                  |   | Quarter |   |
|-----------------------|--------|---------|--------|
|                  |   | First   |   |   | Second |   |   | Third |   |   | Fourth |   |
| 2010:                 |   |    |   |   |   |   |   |   |   |   |   |   |
| Total revenues        |   | $       | 71,228 |   |   | $ | (248,685 | ) |   | $ | 30,672 |   |   | $ | 159,241 |   |
| Total expenses        |   |    | 43,376 |   |   |   | 40,305 |   |   |   | 37,203 |   |   |   | 32,325 |   |
| Net (loss) income     |   | $       | 27,852 |   |   | $ | (288,990 | ) |   | $ | (6,531 | ) |   | $ | 126,916 |   |
|                  |   |    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Net (loss) income per |   |    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| limited partners unit |   | $       | 2.17   |   |   | $ | (23.03 | ) |   | $ | (.56 | ) |   | $ | 10.05 |   |

|                  |   | Quarter |    |
|-----------------------|--------|---------|---------|
|                  |   | First   |    |   | Second |   |   | Third |   |   | Fourth |   |
| 2009:                 |   |    |    |   |   |   |   |   |   |   |   |   |
| Total revenues        |   | $       | 25,525  |   |   | $ | 45,198 |   |   | $ | 65,118 |   |   | $ | 107,571 |   |
| Total expenses        |   |    | 49,140  |   |   |   | 41,093 |   |   |   | 42,225 |   |   |   | 31,893 |   |
| Net income (loss)     |   | $       | (23,615 | ) |   | $ | 4,105 |   |   | $ | 22,893 |   |   | $ | 75,678 |   |
|                  |   |    |    |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Net income (loss) per |   |    |    |   |   |   |   |   |   |   |   |   |   |   |   |   |
| limited partners unit |   | $       | (1.96   | ) |   | $ | .26 |   |   | $ | 1.77 |   |   | $ | 5.97 |   |

----

Item 

Item 

| ·   | management of the Managing General Partner has evaluated the effectiveness of the disclosure controls and procedures as of the end of the period covered by this report; |
|--------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| ·   | this evaluation was conducted under the supervision and with the participation of management of the Managing General Partner, including the chief executive and chief financial officers of the Managing General Partner; and |
|--------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| ·   | it is the conclusion of chief executive and chief financial officers of the Managing General Partner that these disclosure controls and procedures are effective in ensuring that information that is required to be disclosed by the Partnership in reports filed or submitted with the SEC is recorded, processed, summarized and reported within the time periods specified in the rules and forms established by the SEC. |
|--------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| ·   | pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of our assets; |
|--------------------|--------------------------------------------------------------------------------------------------------------------------------------------------|

| ·   | provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that our receipts and expenditures are being made only in accordance with authorizations of management and our Board of Directors; and |
|--------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| ·   | provide reasonable assurance regarding prevention or timely detection of any unauthorized acquisition, use or disposition of our assets that could have a material effect on the financial statements. |
|--------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

----

Item 

----

Item 

Item 

----

Item 

Item 

Item 14.                   Principal Accounting Fees and Services

| For the Year Ended December 31, |   | 2010   |   |   | 2009   |   |
|---------------------------------|--------|--------|--------|--------|--------|--------|
| Audit Fees                      |   | $      | 19,034 |   |   | $      | 17,163 |   |
| Audit Related Fees              |   |   | -      |   |   |   | - |   |
| Tax Fees                        |   |   | -      |   |   |   | - |   |
| All Other Fees                  |   |   | -      |   |   |   | - |   |
|                            |   |   |   |   |   |   |   |   |
| TOTAL                           |   | $      | 19,034 |   |   | $      | 17,163 |   |

----

Item 

| (a)    | (1)    | Financial Statements:                                                                                                                                                                                |
|--------|--------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|   |   |                                                                                                                                                                                                 |
|   |   | Included in Part II of this report                                                                                                                                                                   |
|   |   |                                                                                                                                                                                                 |
|   |   | Report of Independent Registered Public Accounting Firm                                                                                                                                              |
|   |   | Balance Sheets                                                                                                                                                                                       |
|   |   | Statements of Operations                                                                                                                                                                             |
|   |   | Statements of Changes in Partners' (Deficit) Equity                                                                                                                                                  |
|   |   | Statements of Cash Flows                                                                                                                                                                             |
|   |   | Notes to Financial Statements                                                                                                                                                                        |
|   |   |                                                                                                                                                                                                 |
|   | (2)    | Schedules required by Article 12 of Regulation S-X are either omitted because they are not applicable or because the required information is shown in the financial statements or the notes thereto. |
|   |   |                                                                                                                                                                                                 |
|   | (3)    | Exhibits:                                                                                                                                                                                            |

| 4      | (a)    | Certificate of Limited Partnership of Southwest Royalties Institutional Income Fund X-A, L.P., dated January 29, 1990.  (Incorporated by reference from Partnership's Form 10-K for the fiscal year ended December 31, 1990.) |
|--------|--------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|   |   |                                                                                                                                                                                                                                    |
|   | (b)    | Agreement of Limited Partnership of Southwest Royalties Institutional Income Fund X-A, L.P. dated January 29, 1990.  (Incorporated by reference from Partnership's Form 10-K for the fiscal year ended December 31, 1990.)    |
|   |   |                                                                                                                                                                                                                                    |
|   | 31.1   | Rule 13a-14(a)/15d-14(a) Certification                                                                                                                                                                                                  |
|   | 31.2   | Rule 13a-14(a)/15d-14(a) Certification                                                                                                                                                                                                  |
|   | 32.1   | Certification of Chief Executive Officer and Chief Financial Officer Pursuant to 18 U.S.C. Section 1350, as adopted Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002                                                           |

----

Glossary 

----

----

Signatures

|   | Southwest Royalties Institutional Income Fund |
|--------|-----------------------------------------------|
|   | X-A, L.P., a Delaware limited partnership     |
|   |                                          |
| By:    | Southwest Royalties, Inc., Managing           |
|   | General Partner                               |
|   |                                          |
|   |                                          |
| By:    | /s/ Mel G. Riggs                              |
|   | Mel G. Riggs                                  |
|   | President and Chief Executive Officer         |
|   |                                          |
| Date:  | March 29, 2011                                |

|                                                                                  |   |                                                                                  |
|---------------------------------------------------------------------------------------|--------|---------------------------------------------------------------------------------------|
| /s/ Clayton W Williams                                                                |   | /s/ Mel G. Riggs                                                                      |
| Clayton W. Williams, Chairman of the Board                                            |   | Mel G. Riggs, President, Chief Executive                                              |
| and a Director                                                                        |   | Officer and a Director                                                                |
|                                                                                  |   |                                                                                  |
| Date:           March 29, 2011 |   | Date:           March 29, 2011 |
|                                                                                  |   |                                                                                  |
|                                                                                  |   |                                                                                  |
|                                                                                  |   |                                                                                  |
| /s/ Michael L. Pollard                                                                |   |                                                                                  |
| Michael L. Pollard, Senior Vice President                                             |   |                                                                                  |
| and Chief Financial Officer                                                           |   |                                                                                  |
|                                                                                  |   |                                                                                  |
| Date:           March 29, 2011 |   |                                                                                  |
|                                                                                  |   |                                                                                  |
|                                                                                  |   |                                                                                  |