UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D. C. 20549


                                    FORM 10-Q


 / 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 No. 33-26097-10


                        PARKER & PARSLEY 90-C CONV., L.P.
             (Exact name of Registrant as specified in its charter)


               Delaware                                      75-2347264
    (State or other jurisdiction of                       (I.R.S. Employer
     incorporation or organization)                    Identification Number)

303 West Wall, Suite 101, Midland, Texas                        79701
(Address of principal executive offices)                      (Zip code)

       Registrant's Telephone Number, including area code : (915) 683-4768


                                 Not applicable
              (Former name, former address and former fiscal year,
                          if changed since last report)


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 / /

                               Page 1 of 11 pages.
                            Exhibit index on page 10.


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                        PARKER & PARSLEY 90-C CONV., L.P.

                                TABLE OF CONTENTS


                                                                          Page
                          Part I. Financial Information

Item 1.   Financial Statements

          Balance Sheets as of September 30, 1997 and
             December 31, 1996   .......................................    3

          Statements of Operations for the three and nine
            months ended September 30, 1997 and 1996....................    4

          Statement of Partners' Capital for the nine months
            ended September 30, 1997....................................    5

          Statements of Cash Flows for the nine months ended
            September 30, 1997 and 1996.................................    6

          Notes to Financial Statements.................................    7

Item 2.   Management's Discussion and Analysis of Financial
            Condition and Results of Operations.........................    7


                     Part II. Other Information

Item 6.   Exhibits and Reports on Form 8-K..............................   10

          27.   Financial Data Schedule

          Signatures....................................................   11



                                        2

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                        PARKER & PARSLEY 90-C CONV., L.P.
                        (A Delaware Limited Partnership)

                          Part I. Financial Information

Item 1.   Financial Statements

                                 BALANCE SHEETS

                                                   September 30,    December 31,
                                                       1997            1996
                                                   ------------     -----------
                                                    (Unaudited)
                 ASSETS

Current assets:
   Cash and cash equivalents, including interest
     bearing deposits of $92,676 at September 30
     and $79,483 at December 31                    $     92,788     $    79,564
   Accounts receivable - oil and gas sales               63,195         124,287
                                                    -----------      ----------
            Total current assets                        155,983         203,851
                                                    -----------      ----------
Oil and gas properties - at cost, based on the
   successful efforts accounting method               5,750,858       5,744,947
Accumulated depletion                                (4,366,467)     (4,287,671)
                                                    -----------      ----------
            Net oil and gas properties                1,384,391       1,457,276
                                                    -----------      ----------
                                                   $  1,540,374     $ 1,661,127
                                                    ===========      ==========

LIABILITIES AND PARTNERS' CAPITAL

Current liabilities:
   Accounts payable - affiliate                    $     26,967     $    17,442
Partners' capital:
   Managing general partner                              15,103          16,406
   Limited partners (7,531 interests)                 1,498,304       1,627,279
                                                    -----------      ----------
                                                      1,513,407       1,643,685
                                                    -----------      ----------
                                                   $  1,540,374     $ 1,661,127
                                                    ===========      ==========


The financial information included as of September 30, 1997 has been prepared by
           management without audit by independent public accountants.

   The accompanying notes are an integral part of these financial statements.

                                        3

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                        PARKER & PARSLEY 90-C CONV., L.P.
                        (A Delaware Limited Partnership)

                            STATEMENTS OF OPERATIONS
                                   (Unaudited)



                                   Three months ended      Nine months ended
                                      September 30,           September 30,
                                 ---------------------   ---------------------
                                    1997       1996         1997        1996
                                 ---------   ---------   ---------   ---------
Revenues:
   Oil and gas                   $ 145,486   $ 189,248   $ 490,257   $ 584,930
   Interest                          1,450       1,443       4,389       3,651
   Gain (loss) on disposition
     of assets                           7          (7)        800      (6,750)
                                  --------    --------    --------    --------
                                   146,943     190,684     495,446     581,831
                                  --------    --------    --------    --------
Costs and expenses:
   Oil and gas production           73,715      78,363     239,766     247,575
   General and administrative        5,888       6,029      16,906      18,554
   Depletion                        26,566      23,532      78,796      86,923
                                  --------    --------    --------    --------
                                   106,169     107,924     335,468     353,052
                                  --------    --------    --------    --------
Net income                       $  40,774   $  82,760   $ 159,978   $ 228,779
                                  ========    ========    ========    ========
Allocation of net income:
   Managing general partner      $     408   $     828   $   1,600   $   2,288
                                  ========    ========    ========    ========
   Limited partners              $  40,366   $  81,932   $ 158,378   $ 226,491
                                  ========    ========    ========    ========
Net income per limited
   partnership interest          $    5.36   $   10.87   $   21.03   $   30.07
                                  ========    ========    ========    ========
Distributions per limited
   partnership interest          $   10.27   $   12.96   $   38.16   $   37.01
                                  ========    ========    ========    ========



         The financial information included herein has been prepared by
           management without audit by independent public accountants.

   The accompanying notes are an integral part of these financial statements.

                                        4

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                        PARKER & PARSLEY 90-C CONV., L.P.
                        (A Delaware Limited Partnership)

                         STATEMENT OF PARTNERS' CAPITAL
                                   (Unaudited)




                                     Managing
                                     general       Limited
                                     partner       partners         Total
                                    ---------     ----------     ----------

Balance at January 1, 1997          $  16,406     $1,627,279     $1,643,685

    Distributions                      (2,903)      (287,353)      (290,256)

    Net income                          1,600        158,378        159,978
                                     --------      ---------      ---------

Balance at September 30, 1997       $  15,103     $1,498,304     $1,513,407
                                     ========      =========      =========




         The financial information included herein has been prepared by
           management without audit by independent public accountants.

   The accompanying notes are an integral part of these financial statements.

                                        5

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                        PARKER & PARSLEY 90-C CONV., L.P.
                        (A Delaware Limited Partnership)

                            STATEMENTS OF CASH FLOWS
                                   (Unaudited)


                                                          Nine months ended
                                                             September 30,
                                                      ------------------------
                                                          1997         1996
                                                      ----------    ----------
Cash flows from operating activities:
   Net income                                         $  159,978    $  228,779
   Adjustments to reconcile net income to
     net cash provided by operating activities:
        Depletion                                         78,796        86,923
        (Gain) loss on disposition of assets                (800)        6,750
   Changes in assets and liabilities:
        (Increase) decrease in accounts receivable        61,092       (10,164)
        Increase (decrease) in accounts payable            9,525       (18,395)
                                                       ---------     ---------
           Net cash provided by operating activities     308,591       293,893
                                                       ---------     ---------
Cash flows from investing activities:
   Additions to oil and gas properties                    (5,911)       (3,875)
   Proceeds from disposition of assets                       800         4,442
                                                       ---------     ---------
           Net cash provided by (used in) investing
             activities                                   (5,111)          567
                                                       ---------     ---------
Cash flows from financing activities:
   Cash distributions to partners                       (290,256)     (281,565)
                                                       ---------     ---------
Net increase in cash and cash equivalents                 13,224        12,895
Cash and cash equivalents at beginning of period          79,564        82,151
                                                       ---------     ---------
Cash and cash equivalents at end of period            $   92,788    $   95,046
                                                       =========     =========

         The financial information included herein has been prepared by
           management without audit by independent public accountants.

   The accompanying notes are an integral part of these financial statements.

                                        6

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                        PARKER & PARSLEY 90-C CONV., L.P.
                        (A Delaware Limited Partnership)

                          NOTES TO FINANCIAL STATEMENTS
                               September 30, 1997
                                   (Unaudited)

Note 1.     Basis of presentation

In the opinion of  management,  the unaudited  financial  statements of Parker &
Parsley 90-C Conv.,  L.P. (the  "Partnership")  as of September 30, 1997 and for
the  three  and nine  months  ended  September  30,  1997 and 1996  include  all
adjustments and accruals consisting only of normal recurring accrual adjustments
which are  necessary  for a fair  presentation  of the  results  for the interim
period.  These interim results are not  necessarily  indicative of results for a
full year.  Certain  reclassifications  have been made to prior period financial
statements to conform to the 1997 financial presentations.

Certain  information  and  footnote  disclosure  normally  included in financial
statements prepared in accordance with generally accepted accounting  principles
have been  condensed  or  omitted  in this Form 10-Q  pursuant  to the rules and
regulations of the Securities and Exchange Commission.  The financial statements
should  be read in  conjunction  with the  financial  statements  and the  notes
thereto  contained in the  Partnership's  Report on Form 10-K for the year ended
December 31, 1996, as filed with the Securities and Exchange Commission,  a copy
of which is available upon request by writing to Rich Dealy,  Vice President and
Controller, 303 West Wall, Suite 101, Midland, Texas 79701.

Item 2.     Management's Discussion and Analysis of Financial Condition
              and Results of Operations (1)

As of August 8, 1997, Pioneer Natural Resources USA, Inc. ("Pioneer USA") became
the  general  partner  of  the  Partnership.   Prior  to  August  8,  1997,  the
Partnership's general partner was Parker & Parsley Development L.P. ("PPDLP"), a
wholly-owned  subsidiary  of  Parker &  Parsley  Petroleum  Company  ("Parker  &
Parsley").  On  August  7,  1997,  Parker  &  Parsley  and  Mesa  Inc.  received
shareholder  approval  to merge and create  Pioneer  Natural  Resources  Company
("Pioneer").  On August 8, 1997,  PPDLP was merged with and into  Pioneer USA, a
wholly-owned  subsidiary  of  Pioneer,  resulting  in Pioneer USA  becoming  the
general  partner of the Partnership as PPDLP's  successor by merger.  For a more
complete description of the Parker & Parsley and Mesa Inc. merger, see Pioneer's
Registration  Statement  on Form S-4 as filed  with the  Securities and Exchange
Commission.

Results of Operations

Nine months ended September 30, 1997 compared with nine months ended
   September 30, 1996

Revenues:

The Partnership's  oil and gas revenues  decreased 16% to $490,257 from $584,930
for the nine  months  ended  September  30,  1997 as compared to the nine months
ended September 30, 1996. The decrease in  revenues  resulted  from  declines in

                                        7

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barrels of oil and mcf of gas  produced  and sold and a decrease  in the average
price  received  per barrel of oil,  offset by an increase in the average  price
received per mcf of gas. For the nine months ended  September  30, 1997,  19,209
barrels  of oil were sold  compared  to 22,429  for the same  period in 1996,  a
decrease of 3,220 barrels, or 14%. For the nine months ended September 30, 1997,
45,111 mcf of gas were sold  compared to 49,479 mcf for the same period in 1996,
a  decrease  of 4,368  mcf,  or 9%. Due to the  decline  characteristics  of the
Partnership's  properties,  management  expects a certain  amount of  decline in
production  to  continue  in the  future  until the  Partnership's  economically
recoverable reserves are fully depleted.

The average price received per barrel of oil decreased $1.18, or 6%, from $20.97
for the nine months  ended  September  30, 1996 to $19.79 for the same period in
1997,  while the average  price  received per mcf of gas increased 5% from $2.32
during the nine months  ended  September  30, 1996 to $2.44 in 1997.  The market
price  for oil and gas has  been  extremely  volatile  in the past  decade,  and
management expects a certain amount of volatility to continue in the foreseeable
future.  The Partnership may therefore sell its future oil and gas production at
average  prices lower or higher than that received  during the nine months ended
September 30, 1997.

Gain on  disposition  of assets of $800 for the nine months ended  September 30,
1997 was  attributable  to credits  received  from the  disposal  of oil and gas
equipment on one fully  depleted  well.  Loss on disposition of assets of $6,750
was recognized  during the nine months ended September 30, 1996 from the sale of
one gas well to Costilla Energy L.L.C.

Costs and Expenses:

Total  costs and  expenses  decreased  to  $335,468  for the nine  months  ended
September  30,  1997 as compared  to  $353,052  for the same  period in 1996,  a
decrease of  $24,334,  or 7%. This  decrease  was due to declines in  depletion,
production costs and general and administrative expenses ("G&A").

Production  costs were $239,766 for the nine months ended September 30, 1997 and
$247,575 for the same period in 1996, resulting in a $7,809 decrease, or 3%. The
decrease was the result of lower well  maintenance  costs and production  taxes,
offset by a slight increase in ad valorem taxes.

G&A's  components are independent  accounting and engineering  fees and managing
general  partner  personnel  and  operating  costs.   During  this  period,  G&A
decreased, in aggregate, 9% from $18,554 for the nine months ended September 30,
1996 to $16,906 for the same period in 1997.

Depletion  was $78,796 for the nine months ended  September 30, 1997 compared to
$86,923 for the same period in 1996,  representing a decrease of $8,127,  or 9%.
This decrease was primarily attributable to a decline in oil production of 3,220
barrels for the nine  months  ended  September  30, 1997 as compared to the same
period in 1996,  offset by a decline in oil reserves  during 1997 as a result of
lower commodity prices.

                                        8

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Three months ended September 30, 1997 compared with three months ended
   September 30, 1996

Revenues:

The Partnership's  oil and gas revenues  decreased 23% to $145,486 from $189,248
for the three  months ended  September  30, 1997 as compared to the three months
ended  September 30, 1996. The decrease in revenues  resulted from lower average
prices received per barrel of oil and mcf of gas and a decline in barrels of oil
produced and sold,  offset by an increase in mcf of gas  produced and sold.  For
the three  months  ended  September  30,  1997,  6,195  barrels of oil were sold
compared to 7,242 for the same period in 1996, a decrease of 1,047  barrels,  or
15%. For the three months ended September 30, 1997,  15,309 mcf of gas were sold
compared to 14,809 for the same  period in 1996,  an increase of 500 mcf, or 3%.
The increase in gas production was the result of operational  changes on several
wells. The decrease in oil production was due to the decline  characteristics of
the Partnership's oil properties.

The average  price  received per barrel of oil  decreased  $3.36,  or 16%,  from
$21.73 for the three  months  ended  September  30,  1996 to $18.37 for the same
period in 1997,  while the average  price  received per mcf of gas  decreased 4%
from $2.15 during the three months ended September 30, 1996 to $2.07 in 1997.

Costs and Expenses:

Total costs and  expenses  decreased  to  $106,169  for the three  months  ended
September  30,  1997 as compared  to  $107,924  for the same  period in 1996,  a
decrease of $1,755.  This decrease was due to declines in  production  costs and
G&A, offset by an increase in depletion.

Production  costs were $73,715 for the three months ended September 30, 1997 and
$78,363 for the same period in 1996, resulting in a $4,648 decrease,  or 6%. The
decrease was the result of lower well  maintenance  costs and production  taxes,
offset by an increase in ad valorem taxes.

G&A's  components are independent  accounting and engineering  fees and managing
general partner personnel and operating costs. During this period, G&A decreased
slightly from $6,029 for the three months ended September 30, 1996 to $5,888 for
the same period in 1997.

Depletion was $26,566 for the three months ended  September 30, 1997 compared to
$23,532 for the same period in 1996, representing an increase of $3,034, or 13%,
primarily  attributable to a decline in oil reserves during the third quarter of
1997 as a result of lower commodity prices.

Liquidity and Capital Resources

Net Cash Provided by Operating Activities

Net cash  provided by operating  activities  increased  $14,698  during the nine
months ended  September 30, 1997 from the same period ended  September 30, 1996.
This increase was due to a decrease in G&A and production costs paid,  offset by
a decline in oil and gas sales receipts.

                                        9

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Net Cash Provided by (Used in) Investing Activities

The  Partnership's  investing  activities during the nine months ended September
30, 1997 and 1996  included  expenditures  related to equipment  replacement  on
various oil and gas properties.

Proceeds of $800 from the salvage of equipment on one fully  depleted  well were
received  during the nine months ended  September  30, 1997.  Proceeds of $4,442
from  the sale of one gas well  were  received  during  the  nine  months  ended
September 30, 1996.

Net Cash Used in Financing Activities

Cash was  sufficient  for the nine  months  ended  September  30,  1997 to cover
distributions to the partners of $290,256 of which $2,903 was distributed to the
managing  general  partner and  $287,353 to the limited  partners.  For the same
period ended  September 30, 1996, cash was sufficient for  distributions  to the
partners of $281,565 of which $2,813 was  distributed  to the  managing  general
partner and $278,752 to the limited partners.

It is expected  that future net cash  provided by operating  activities  will be
sufficient for any capital expenditures and any distributions. As the production
from the properties declines, distributions are also expected to decrease.

---------------

(1)   "Item 2. Management's  Discussion and Analysis of Financial  Condition and
      Results of Operations"  contains  forward looking  statements that involve
      risks and uncertainties.  Accordingly, no assurances can be given that the
      actual  events  and  results  will not be  materially  different  than the
      anticipated results described in the forward looking statements.

                           Part II. Other Information

Item 6.     Exhibits and Reports on Form 8-K

(a)  Exhibits

     27.  Financial Data Schedule

(b)  Reports on Form 8-K - none



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                        PARKER & PARSLEY 90-C CONV., L.P.
                        (A Delaware Limited Partnership)



                               S I G N A T U R E S



       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.


                                           PARKER & PARSLEY 90-C CONV., L.P.

                                    By:    Pioneer Natural Resources USA, Inc.,
                                             Managing General Partner




Dated:  November 10, 1997           By:    /s/ Rich Dealy
                                           ----------------------------------
                                           Rich Dealy, Vice President and
                                             Controller



                                       11

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