Page 3 of 14
                                 FORM 10-Q
                                     
                                     
                    SECURITIES AND EXCHANGE COMMISSION
                         WASHINGTON, D. C.  20549

(Mark One)

(X)  QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
     EXCHANGE ACT OF 1934

For the quarterly period ended September 30, 1997

                                    OR

( )  TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
     EXCHANGE ACT OF 1934

For the transition period from _________________ to _______________

Commission file number 0-20298

         SOUTHWEST ROYALTIES INSTITUTIONAL 1990-91 INCOME PROGRAM
          Southwest Royalties Institutional Income Fund X-C, L.P.
                  (Exact name of registrant as specified
                   in its limited partnership agreement)

Delaware                                          75-2374449
(State or other jurisdiction of                        (I.R.S. Employer
incorporation or organization)                         Identification No.)

                       407 N. Big Spring, Suite 300
                  _________Midland, Texas 79701_________
                 (Address of principal executive offices)
                                     
                      ________(915) 686-9927________
                      (Registrant's telephone number,
                           including area code)

Indicate  by  check  mark  whether 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 _____
                                     
         The total number of pages contained in this report is 14.

<PAGE>

                      PART I. - FINANCIAL INFORMATION

Item 1.  Financial Statements

The  unaudited  condensed financial statements included  herein  have  been
prepared  by  the Registrant (herein also referred to as the "Partnership")
in  accordance  with generally accepted accounting principles  for  interim
financial information and with the instructions to Form 10-Q and Rule 10-01
of Regulation S-X.  Accordingly, they do not include all of the information
and  footnotes  required  by generally accepted accounting  principles  for
complete   financial  statements.   In  the  opinion  of  management,   all
adjustments necessary for a fair presentation have been included and are of
a  normal  recurring nature.  The financial statements should  be  read  in
conjunction with the audited financial statements and the note thereto  for
the  year ended December 31, 1996 which are found in the Registrant's  Form
10-K  Report  for  1996 filed with the Securities and Exchange  Commission.
The December 31, 1996 balance sheet included herein has been taken from the
Registrant's  1996 Form 10-K Report.  Operating results for the  three  and
nine  month periods ended September 30, 1997 are not necessarily indicative
of the results that may be expected for the full year.

<PAGE>

          Southwest Royalties Institutional Income Fund X-C, L.P.
                                     
                              Balance Sheets

                                              September 30,   December 31,
                                                   1997           1996
                                              -------------   ------------
                                               (unaudited)
Assets

Current assets
 Cash and cash equivalents                     $   16,227        170,421
 Receivable from Managing General Partner          87,575        131,006
---------                                      ---------
     Total current assets                         103,802        301,427
                                                ---------      ---------
Oil and gas properties - using the
 full cost method of accounting                 2,244,628      2,244,628
  Less accumulated depreciation,
   depletion and amortization                   1,620,479      1,554,479
                                                ---------      ---------
     Net oil and gas properties                   624,149        690,149
                                                ---------      ---------
                                               $  727,951        991,576
                                                =========      =========

Liabilities and Partners' Equity

Current liability - Distribution payable       $       35              -
                                                ---------      ---------
Partners' equity
 General partners                                (21,004)        (1,238)
 Limited partners                                 748,920        992,814
                                                ---------      ---------
     Total partners' equity                       727,916        991,576
                                                ---------      ---------
                                               $  727,951        991,576
                                                =========      =========
<PAGE>

          Southwest Royalties Institutional Income Fund X-C, L.P.
                                     
                         Statements of Operations
                                (unaudited)


                                Three Months Ended    Nine Months Ended
                                  September 30,         September 30,
                                  1997      1996        1997      1996

Revenues

Income from net profits
 interests                   $    74,896   117,206     305,289   360,059
Interest                             500     2,447       2,858     6,190
                                  ------   -------     -------   -------
                                  75,396   119,653     308,147   366,249
                                  ------   -------     -------   -------
Expenses

General and administrative         9,097     9,140      34,307    34,529
Depreciation, depletion and
 amortization                     20,000    33,620      66,000   101,860
                                  ------   -------     -------   -------
                                  29,097    42,760     100,307   136,389
                                  ------   -------     -------   -------
Net income                   $    46,299    76,893     207,840   229,860
                                  ======   =======     =======   =======



Net income allocated to:

 Managing General Partner    $     5,967     9,946      24,646    29,855
                                  ======   =======     =======   =======
 General Partner             $       663     1,105       2,738     3,317
                                  ======   =======     =======   =======
 Limited Partners            $    39,669    65,842     180,456   196,688
                                  ======   =======     =======   =======
  Per limited partner unit   $      6.63     11.00       30.16     32.87
                                  ======   =======     =======   =======

<PAGE>

          Southwest Royalties Institutional Income Fund X-C, L.P.
                                     
                         Statements of Cash Flows
                                (unaudited)


                                                      Nine Months Ended
                                                        September 30,
                                                       1997       1996
Cash flows from operating activities

 Cash received from income from net
  profits interests                                $  348,720    360,701
 Cash paid to suppliers                              (34,307)   (34,529)
 Interest received                                      2,858      6,190
                                                       ------    -------

  Net cash provided by operating activities           317,271    332,362
                                                      -------    -------

Cash flows provided by investing activities

 Cash received from sale of oil and gas
  property interest                                         -    305,594
                                                      -------    -------

Cash flows used in financing activities

 Distributions to partners                          (471,465)  (439,266)
                                                      -------    -------
Net increase (decrease) in cash and cash
 equivalents                                        (154,194)    198,690

 Beginning of period                                  170,421     29,574
                                                      -------    -------
 End of period                                     $   16,227    228,264
=======                                            =======

                                                             (continued)
<PAGE>

          Southwest Royalties Institutional Income Fund X-C, L.P.
                                     
                    Statements of Cash Flows, continued
                                (unaudited)


                                                      Nine Months Ended
                                                        September 30,
                                                       1997       1996
Reconciliation of net income to net cash
 provided by operating activities

Net income                                         $  207,840    229,860

Adjustments to reconcile net income to net
 cash provided by operating activities

 Depreciation, depletion and amortization              66,000    101,860
 Decrease in receivables                               43,431        642
                                                      -------    -------
Net cash provided by operating activities          $  317,271    332,362
                                                      =======    =======


<PAGE>

Item 2.  Management's  Discussion and Analysis of Financial  Condition  and
       Results of Operations

General

Southwest Royalties Institutional Income Fund X-C, L.P. was organized as  a
Delaware limited partnership on September 20, 1991.  The offering  of  such
limited  partnership interests began October 1, 1991 as  part  of  a  shelf
offering registered under the name Southwest Royalties Institutional  1990-
91  Income Program.  Minimum capital requirements for the Partnership  were
met on January 28, 1992, with the offering of limited partnership interests
concluding April 30, 1992, with 340 limited partners purchasing 5,983 units
for $2,991,500.

The Partnership was formed to acquire royalty and net profits interests  in
producing  oil  and  gas properties, to produce and market  crude  oil  and
natural  gas  produced  from such properties, and  to  distribute  the  net
proceeds from operations to the limited and general partners.  Net revenues
from  producing  oil  and gas properties will not be  reinvested  in  other
revenue  producing  assets except to the extent that production  facilities
and wells are improved or reworked or where methods are employed to improve
or enable more efficient recovery of oil and gas reserves.

Increases   or   decreases   in  Partnership   revenues   and,   therefore,
distributions  to partners will depend primarily on changes in  the  prices
received  for  production,  changes in volumes of  production  sold,  lease
operating  expenses, enhanced recovery projects, offset drilling activities
pursuant to farmout arrangements, sales of properties, and the depletion of
wells.  Since wells deplete over time, production can generally be expected
to decline from year to year.

Well  operating costs and general and administrative costs usually decrease
with   production   declines;  however,  these  costs  may   not   decrease
proportionately.  Net income available for distribution to the partners  is
therefore expected to fluctuate in later years based on these factors.

Based  on  current conditions, management anticipates performing  workovers
during   1997  to  enhance  production.   The  Partnership  could  possibly
experience  the  following changes; a little less than  normal  decline  in
1997, with no decline in 1998 and thereafter, experience a low decline.


<PAGE>

Results of Operations

A.  General Comparison of the Quarters Ended September 30, 1997 and 1996

The  following  table  provides certain information  regarding  performance
factors for the quarters ended September 30, 1997 and 1996:

                                                 Three Months
                                                    Ended        Percentage
                                                September 30,     Increase
                                                1997      1996   (Decrease)

Average price per barrel of oil            $   16.87     20.83    (19%)
Average price per mcf of gas               $    2.14      1.84      16%
Oil production in barrels                     10,900    11,600     (6%)
Gas production in mcf                         18,300    19,000     (4%)
Income from net profits interests          $  74,896   117,206    (36%)
Partnership distributions                  $ 115,000   180,000    (36%)
Limited partner distributions              $ 103,500   162,000    (36%)
Per unit distribution to limited partners  $   17.30     27.08    (36%)
Number of limited partner units                5,983     5,983

Revenues

The  Partnership's income from net profits interests decreased  to  $74,896
from  $117,206  for  the  quarters  ended  September  30,  1997  and  1996,
respectively,  a  decrease  of 36%.  The principal  factors  affecting  the
comparison  of  the  quarters ended September 30,  1997  and  1996  are  as
follows:

1.   The  average  price  for a barrel of oil received by  the  Partnership
     decreased  during the quarter ended September 30, 1997 as compared  to
     the  quarter  ended  September 30, 1996 by 19%, or $3.96  per  barrel,
     resulting  in a decrease of approximately $45,900 in income  from  net
     profits  interests.  Oil sales represented 82% of total  oil  and  gas
     sales  during the quarter ended September 30, 1997 as compared to  87%
     during the quarter ended September 30, 1996.

     The  average  price  for  an mcf of gas received  by  the  Partnership
     increased during the same period by 16%, or $.30 per mcf, resulting in
     an  increase  of  approximately $5,700  in  income  from  net  profits
     interests.

     The net total decrease in income from net profits interests due to the
     change in prices received from oil and gas production is approximately
     $40,200.  The market price for oil and gas has been extremely volatile
     over  the  past  decade, and management expects a  certain  amount  of
     volatility to continue in the foreseeable future.

<PAGE>

2. Oil  production  decreased approximately 700 barrels or  6%  during  the
   quarter  ended  September  30, 1997 as compared  to  the  quarter  ended
   September 30, 1996, resulting in a decrease of approximately $11,800  in
   income from net profits interests.

    Gas  production decreased approximately 700 mcf or 4% during  the  same
    period, resulting in a decrease of approximately $1,500 in income  from
    net profits interests.

    The  total  decrease in income from net profits interests  due  to  the
    change in production is approximately $13,300.

3.  Lease   operating  costs  and  production  taxes  were  7%  lower,   or
    approximately $11,700 less during the quarter ended September 30,  1997
    as compared to the quarter ended September 30, 1996.

Costs and Expenses

Total costs and expenses decreased to $29,097 from $42,760 for the quarters
ended  September 30, 1997 and 1996, respectively, a decrease of  32%.   The
decrease  is  the  result of lower general and administrative  expense  and
depletion expense.

1.  General and administrative costs consists of independent accounting and
    engineering  fees,  computer services, postage,  and  Managing  General
    Partner  personnel costs.  General and administrative  costs  decreased
    less  than  1% or approximately $40 during the quarter ended  September
    30, 1997 as compared to the quarter ended September 30, 1996.

2.  Depletion  expense decreased to $20,000 for the quarter ended September
    30,  1997 from $32,000 for the same period in 1996.  This represents  a
    decrease  of 38%.  Depletion is calculated using the units  of  revenue
    method  of  amortization based on a percentage of current period  gross
    revenues  to  total future gross oil and gas revenues, as estimated  by
    the  Partnership's  independent  petroleum  consultants.   Contributing
    factors  to  the  decline in depletion expense between the  comparative
    periods  were  the increase in the price of oil used to  determine  the
    Partnership's reserves for January 1, 1997 as compared to 1996 and  the
    decline in gross oil and gas revenues.

<PAGE>

B.   General Comparison of the Nine Month Periods Ended September 30,  1997
and 1996

The  following  table  provides certain information  regarding  performance
factors for the nine month periods ended September 30, 1997 and 1996:

                                                 Nine Months
                                                    Ended        Percentage
                                                September 30,     Increase
                                                1997      1996   (Decrease)

Average price per barrel of oil            $   18.57     19.31    (4%)
Average price per mcf of gas               $    2.31      1.96     18%
Oil production in barrels                     33,700    37,100    (9%)
Gas production in mcf                         55,500    57,000    (3%)
Income from net profits interests          $ 305,289   360,059   (15%)
Partnership distributions                  $ 471,500   439,266      7%
Limited partner distributions              $ 424,350   396,566      7%
Per unit distribution to limited partners  $   70.93     66.28      7%
Number of limited partner units                5,983     5,983

Revenues

The  Partnership's income from net profits interests decreased to  $305,289
from  $360,059  for  the nine months ended September  30,  1997  and  1996,
respectively,  a  decrease  of 15%.  The principal  factors  affecting  the
comparison  of  the nine months ended September 30, 1997 and  1996  are  as
follows:

1.  The  average  price  for a barrel of oil received  by  the  Partnership
    decreased  during the nine months ended September 30, 1997 as  compared
    to  the nine months ended September 30, 1996 by 4%, or $.74 per barrel,
    resulting  in  a decrease of approximately $27,500 in income  from  net
    profits  interests.  Oil sales represented 83% of  total  oil  and  gas
    sales  during the nine months ended September 30, 1997 as  compared  to
    87% during the nine months ended September 30, 1996.

    The  average  price  for  an  mcf of gas received  by  the  Partnership
    increased during the same period by 18%, or $.35 per mcf, resulting  in
    an  increase  of  approximately $20,000  in  income  from  net  profits
    interests.

    The  net total decrease in income from net profits interests due to the
    change  in prices received from oil and gas production is approximately
    $7,500.   The market price for oil and gas has been extremely  volatile
    over  the  past  decade, and management expects  a  certain  amount  of
    volatility to continue in the foreseeable future.

<PAGE>

2.  Oil  production decreased approximately 3,400 barrels or 9% during  the
    nine  months  ended September 30, 1997 as compared to the  nine  months
    ended  September  30,  1996, resulting in a decrease  of  approximately
    $63,100 in income from net profits interests.

    Gas  production decreased approximately 1,500 mcf or 3% during the same
    period, resulting in a decrease of approximately $3,500 in income  from
    net profits interests.

    The  total  decrease in income from net profits interests  due  to  the
    change in production is approximately $66,600.

3.  Lease   operating  costs  and  production  taxes  were  4%  lower,   or
    approximately  $20,200 less during the nine months ended September  30,
    1997 as compared to the nine months ended September 30, 1996.

Costs and Expenses

Total  costs and expenses decreased to $100,307 from $136,389 for the  nine
months ended September 30, 1997 and 1996, respectively, a decrease of  26%.
The  decrease is the result of lower general and administrative expense and
depletion expense.

1.  General and administrative costs consists of independent accounting and
    engineering  fees,  computer services, postage,  and  Managing  General
    Partner personnel costs.  General and administrative costs decreased 1%
    or  approximately $200 during the nine months ended September 30,  1997
    as compared to the nine months ended September 30, 1996.

2.  Depletion  expense  decreased to $66,000  for  the  nine  months  ended
    September  30,  1997 from $97,000 for the same period  in  1996.   This
    represents a decrease of 32%.  Depletion is calculated using the  units
    of  revenue  method  of amortization based on a percentage  of  current
    period  gross  revenues to total future gross oil and gas revenues,  as
    estimated  by  the  Partnership's  independent  petroleum  consultants.
    Contributing  factors to the decline in depletion expense  between  the
    comparative  periods  were the increase in the price  of  oil  used  to
    determine the Partnership's reserves for January 1, 1997 as compared to
    1996 and the decline in gross oil and gas revenues.

<PAGE>

Liquidity and Capital Resources

The  primary source of cash is from operations, the receipt of income  from
interests in oil and gas properties.  The Partnership knows of no  material
change, nor does it anticipate any such change.

Cash flows provided by operating activities were approximately $317,300  in
the  nine  months  ended  September 30, 1997 as compared  to  approximately
$332,400  in the nine months ended September 30, 1996.  The primary  source
of the 1997 cash flow from operating activities was profitable operations.

There  were  no  cash flows provided by investing activities  in  the  nine
months  ended September 30, 1997 as compared to approximately  $305,600  in
the nine months ended September 30, 1996.

Cash flows used in financing activities were approximately $471,500 in  the
nine  months ended September 30, 1997 as compared to approximately $439,300
in  the  nine  months ended September 30, 1996.  The only use in  financing
activities was the distributions to partners.

Total  distributions during the nine months ended September 30,  1997  were
$471,500  of  which  $424,350 was distributed to the limited  partners  and
$47,150  to  the  general partners.  The per unit distribution  to  limited
partners during the nine months ended September 30, 1997 was $70.93.  Total
distributions during the nine months ended September 30, 1996 were $439,266
of  which  $396,566 was distributed to the limited partners and $42,700  to
the general partners.  The per unit distribution to limited partners during
the nine months ended September 30, 1996 was $66.28.

The  source  for  the  1997  distributions of  $471,500  was  oil  and  gas
operations of approximately $317,300, with the balance from available  cash
on  hand  at  the  beginning  of the period.   The  sources  for  the  1996
distributions  of  $439,266  were oil and gas operations  of  approximately
$332,400  and the sale of oil and gas properties of approximately $305,600,
resulting in excess cash for contingencies or subsequent distributions.

Since  inception of the Partnership, cumulative monthly cash  distributions
of  $2,369,468 have been made to the partners.  As of September  30,  1997,
$2,144,378 or $358.41 per limited partner unit has been distributed to  the
limited partners, representing a 72% return of the capital contributed.

As  of  September 30, 1997, the Partnership had approximately  $103,800  in
working  capital.   The  Managing  General  Partner  knows  of  no  unusual
contractual commitments and believes the revenues generated from operations
are adequate to meet the needs of the Partnership.

<PAGE>

                        PART II - OTHER INFORMATION
                                     

Item 1.  Legal Proceedings

         None

Item 2.  Changes in Securities

         None

Item 3.  Defaults Upon Senior Securities

         None

Item 4.  Submission of Matter to a Vote of Security Holders

         None

Item 5.  Other Information

         None

Item 6.  Exhibits and Reports on Form 8-K

         (a)Exhibits:

             27 Financial Data Schedule

         (b) No reports on Form 8-K were filed during the quarter for
             which this report is filed.
            
            
<PAGE>

                                SIGNATURES


Pursuant  to the requirements 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.

                                   Southwest Royalties Institutional Income
                                   Fund X-C, L.P.
                                   a Delaware limited partnership


By:                                Southwest Royalties, Inc.
Managing General Partner


                                   By:  /s/ Bill E. Coggin
                                        ------------------------------
                                        Bill E. Coggin, Vice President
and Chief Financial Officer

Date:     November 15, 1997

<PAGE>