---

UNITED STATES SECURITIES AND EXCHANGE COMMISSION

Washington, D. C. 20549

FORM 10-K/A

Amendment No. 1

x ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2005

or

 ̈TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

Commission file number: 000-32261

ATP Oil & Gas Corporation

(Exact name of registrant as specified in its charter)



|                         |  |                                     
|------------------------ |  | ------------------------------------
|Texas                    |  | 76-0362774                          
|(State of incorporation) |  | (I.R.S. Employer Identification No.)

4600 Post Oak Place, Suite 200

Houston, Texas 77027

(Address of principal executive offices) (Zip Code)

Registrants telephone number, including area code: (713) 622-3311

Securities Registered Pursuant to Section 12 (b) of the Act:



|                                        |  |                                     
|--------------------------------------- |  | ------------------------------------
|Title of each class                     |  | Name of exchange on which
registered
|Common Stock, par value $.001 per share |  | NASDAQ                              

Securities Registered Pursuant to Section 12 (g) of the Act: None

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 ̈No  x

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.    Yes  x    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. ̈

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  x             Non-accelerated filer ̈

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

The aggregate market value of the voting and non-voting common stock held by non-affiliates of the Registrant as of June 30, 2005 (the last business
day of the Registrants most recently completed second fiscal quarter) was approximately $426,436,897. The number of shares of the Registrants common stock outstanding as of March 9, 2006 was 29,792,934.

DOCUMENTS INCORPORATED BY REFERENCE

None



---



---

EXPLANATORY NOTE

We are filing this Form 10-K/A to amend Part II, Item 9A of our Annual Report on Form 10-K for the fiscal year ended December 31, 2005, which we filed with Securities and Exchange Commission on
March 15, 2006. This amendment is being filed because the first paragraph of Item 9A Controls and Procedures was inadvertently omitted.

The following item has been included in this amendment:

Part II  Item 9A.
Controls and Procedures.

In addition, this amendment includes the following exhibits:



|     |  |                                                                                                                             
|---- |  | ----------------------------------------------------------------------------------------------------------------------------
|     | 
|23.1 |  |  Consent of Independent Registered Public Accounting Firm, with corrected reference to report date.                        
|     | 
|31.1 |  |  Certification of Principal Executive Officer pursuant to Rule 13a-14(a) of the Securities Exchange Act of 1934, the
Act.
|     | 
|31.2 |  |  Certification of Principal Financial Officer pursuant to Rule 13a-14(a) of the Act.                                       

This Form 10-K/A does not reflect events occurring after the filing of our Annual Report on Form
10-K on March 15, 2006 or include, or otherwise modify or update, the disclosure contained therein in any way except as expressly indicated above.

PART II

Item 9A.Controls and Procedures.

Evaluation of Disclosure Controls and Procedures

In
order to ensure that the information we must disclose in our filings with the Securities and Exchange Commission is recorded, processed, summarized, and reported on a timely basis, we have formalized our disclosure controls and procedures. Our
principal executive officer and principal financial officer have reviewed and evaluated the effectiveness of our disclosure controls and procedures, as defined in Exchange Act Rules 13a-15(e) and 15d-15(e), as of December 31, 2005. Based on
such evaluation, such officers have concluded that, as of December 31, 2005, our disclosure controls and procedures were effective in timely alerting them to material information relating to us (and our consolidated subsidiaries) required to be
included in our periodic SEC filings. There has been no change in our internal control over financial reporting during the quarter ended December 31, 2005 that has materially affected, or is reasonably likely to materially affect, our internal
control over financial reporting.

Managements Report on Internal Control Over Financial Reporting

Management of ATP Oil & Gas Corporation (the Company) is responsible for establishing and maintaining adequate internal control over
financial reporting for the Company, as such term is defined in Rules 13a-15(f) and 15d-15(f) under the Securities Exchange Act of 1934. Under the supervision and with the participation of the Companys management, including our principal
executive and principal financial officers, the Company conducted an evaluation of the effectiveness of its internal control over financial reporting based on the framework in Internal Control  Integrated Frameworkissued by the
Committee of Sponsoring Organizations of the Treadway Commission (the COSO Framework). Based on this evaluation under the COSO Framework which was completed on March 13, 2006, management concluded that its internal control over
financial reporting was effective as of December 31, 2005.

Managements assessment of the effectiveness of the Companys
internal control over financial reporting as of December 31, 2005 has been audited by the independent registered public accounting firm who audited the Companys consolidated financial statements as of and for the year ended
December 31, 2005, as stated in their report which is included in our annual report on Form 10-K, which was filed on March 15, 2006.



---

PART IV

Item 15.Exhibits, Financial Statement Schedules.

(a) (1) and (2) Financial Statements
and Financial Statement Schedules

None.

(a) (3) Exhibits



|      |  |                                                                                                                           
|----- |  | --------------------------------------------------------------------------------------------------------------------------
|      | 
|*23.1 |  | Consent of Independent Registered Public Accounting Firm.                                                                 
|      | 
|*31.1 |  | Certification of Principal Executive Officer pursuant to Rule 13a-14(a) of the Securities Exchange Act of 1934, the Act.
|      | 
|*31.2 |  | Certification of Principal Financial Officer pursuant to Rule 13a-14(a) of the Act                                        

---

|* | Filed herewith
|- | --------------



---

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.



|                   |  |  |  |                           |  |                          |  |                                             
|------------------ |  |  |  | ------------------------- |  | ------------------------ |  | --------------------------------------------
|                   |  |  |  | ATP Oil & Gas Corporation
|                   |  |  | 
|Date: May 10, 2006 |  |  |  | By:                       |  | /s/ Albert L. Reese, Jr.
|                   |  |  |  |                           |  |                          |  | Albert L. Reese, Jr. Chief Financial Officer