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. 33-26097-05


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

               Delaware                                      75-2329245
    (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.






                           PARKER & PARSLEY 90-A, 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





                           PARKER & PARSLEY 90-A, 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 $110,597 at September 30
     and $102,316 at December 31                  $    110,817    $    127,525
   Accounts receivable - oil and gas sales              74,429         131,628
                                                   -----------     -----------
          Total current assets                         185,246         259,153
                                                   -----------     -----------
Oil and gas properties - at cost, based on the
   successful efforts accounting method              5,066,728       5,053,096
Accumulated depletion                               (3,274,840)     (3,165,751)
                                                   -----------     -----------
                                                     1,791,888       1,887,345
                                                   -----------     -----------
                                                  $  1,977,134    $  2,146,498
                                                   ===========     ===========
LIABILITIES AND PARTNERS' CAPITAL

Current liabilities:
   Accounts payable - affiliate                   $     22,888    $     18,703
   Accounts payable - other                                -                32
                                                   -----------     -----------
                                                        22,888          18,735
                                                   -----------     -----------
Partners' capital:
   Managing general partner                             19,623          21,358
   Limited partners (6,811 interests)                1,934,623       2,106,405
                                                   -----------     -----------
                                                     1,954,246       2,127,763
                                                   -----------     -----------
                                                  $  1,977,134    $  2,146,498
                                                   ===========     ===========


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





                           PARKER & PARSLEY 90-A, 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                     $ 134,280   $ 165,659   $ 460,038   $ 533,375
  Interest                            1,739       1,901       5,517       5,015
                                   --------    --------    --------    --------
                                    136,019     167,560     465,555     538,390
                                   --------    --------    --------    --------
Costs and expenses:
  Oil and gas production             77,571      78,353     225,929     226,126
  General and administrative          4,633       5,381      15,193      17,180
  Depletion                          34,757      33,014     109,089     132,122
  Loss on disposition of assets         -            13         -        28,717
                                   --------    --------    --------    --------
                                    116,961     116,761     350,211     404,145
                                   --------    --------    --------    --------
Net income                        $  19,058   $  50,799   $ 115,344   $ 134,245
                                   ========    ========    ========    ========
Allocation of net income:
  Managing general partner        $     190   $     508   $   1,153   $   1,342
                                   ========    ========    ========    ========
  Limited partners                $  18,868   $  50,291   $ 114,191   $ 132,903
                                   ========    ========    ========    ========
Net income per limited
  partnership interest            $    2.77   $    7.38   $   16.77   $   19.51
                                   ========    ========    ========    ========
Distributions per limited
  partnership interest            $    9.18   $   13.03   $   41.99   $   38.36
                                   ========    ========    ========    ========

         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





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

                         STATEMENT OF PARTNERS' CAPITAL
                                   (Unaudited)




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

Balance at January 1, 1997          $ 21,358    $2,106,405    $2,127,763

    Distributions                     (2,888)     (285,973)     (288,861)

    Net income                         1,153       114,191       115,344
                                     -------     ---------     ---------

Balance at September 30, 1997       $ 19,623    $1,934,623    $1,954,246
                                     =======     =========     =========



         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





                           PARKER & PARSLEY 90-A, 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                                            $ 115,344    $ 134,245
  Adjustments to reconcile net income to net
     cash provided by operating activities:
       Depletion                                          109,089      132,122
       Loss on disposition of assets                          -         28,717
  Changes in assets and liabilities:
       (Increase) decrease in accounts receivable          57,199       (6,806)
       Increase (decrease) in accounts payable              4,153      (10,620)
                                                         --------     --------
           Net cash provided by operating activities      285,785      277,658
                                                         --------     --------
Cash flows from investing activities:
  Additions to oil and gas properties                     (13,632)      (1,189)
  Proceeds from disposition of assets                         -          6,815
                                                         --------     --------
           Net cash provided by (used in) investing
             activities                                   (13,632)       5,626
                                                         --------     --------
Cash flows from financing activities:
  Cash distributions to partners                         (288,861)    (264,111)
                                                         --------     --------
Net increase (decrease) in cash and cash equivalents      (16,708)      19,173
Cash and cash equivalents at beginning of period          127,525      118,751
                                                         --------     --------
Cash and cash equivalents at end of period              $ 110,817    $ 137,924
                                                         ========     ========

         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





                           PARKER & PARSLEY 90-A, 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-A,  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  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 14% to $460,038 from $533,375
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
barrels  of oil and  mcf  of gas  produced and  sold and  a lower  average price

                                        7





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,  15,814 barrels of
oil were sold  compared  to 18,518 for the same  period in 1996,  a decrease  of
2,704 barrels,  or 15%. For the nine months ended September 30, 1997, 59,805 mcf
of gas were sold  compared to 68,476 mcf for the same period in 1996, a decrease
of 8,671 mcf, or 13%. The  production  volume  decreases were due to the decline
characteristics  of the Partnership's  oil and gas properties.  Because of these
characteristics, 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 4% from $20.60 for the
nine  months  ended  September  30,  1996 to $19.76  for the same  period  ended
September 30, 1997,  while the average  price  received per mcf of gas increased
11% from $2.22 during the nine months ended September 30, 1996 to $2.47 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.

Costs and Expenses:

Total  costs and  expenses  decreased  to  $350,211  for the nine  months  ended
September  30,  1997 as compared  to  $404,145  for the same  period in 1996,  a
decrease  of  $53,934,  or 13%.  This  decrease  was due to  declines in loss on
disposition of assets,  depletion,  general and administrative  expenses ("G&A")
and production costs.

Production  costs were $225,929 for the nine months ended September 30, 1997 and
$226,126 for the same period in 1996, resulting in a $197 decrease. The decrease
was due to a slight  decline in  production  tax due to a decline in oil and gas
sales.

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,  12% from $17,180 for the nine months ended  September
30, 1996 to $15,193 for the same period in 1997.

Depletion was $109,089 for the nine months ended  September 30, 1997 compared to
$132,122  for the same period in 1996,  representing  a decrease of $23,033,  or
17%. This decrease was primarily  attributable to a decline in oil production of
2,704  barrels for the nine months ended  September  30, 1997 as compared to the
same period in 1996.

A loss on disposition of assets of $28,717 was recognized during the nine months
ended  September 30, 1996.  This loss was the result of the sale of one gas well
to Costilla Energy, L.L.C.

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

Revenues:

The Partnership's  oil and gas revenues  decreased 19% to $134,280 from $165,659
for the three  months ended  September  30, 1997 as compared to the three months
ended September 30, 1996.  The decrease in revenues  resulted from a decrease in

                                        8





the average price  received per barrel of oil and declines in barrels of oil and
mcf of gas  produced  and  sold,  offset by an  increase  in the  average  price
received per mcf of gas. For the three months ended  September  30, 1997,  4,967
barrels  of oil were  sold  compared  to 5,618 for the same  period  in 1996,  a
decrease of 651 barrels,  or 12%. For the three months ended September 30, 1997,
20,190 mcf of gas were sold  compared to 21,755 for the same  period in 1996,  a
decrease of 1,565 mcf, or 7%. The  decreases in  production  volumes were due to
the decline characteristics of the Partnership's oil and gas properties.

The average  price  received per barrel of oil  decreased  $3.31,  or 15%,  from
$21.59 for the three  months  ended  September  30,  1996 to $18.28 for the same
period in 1997,  while the average  price  received per mcf of gas  increased 5%
from $2.04 during the three months ended September 30, 1996 to $2.15 in 1997.

Costs and Expenses:

Total costs and  expenses  increased  to  $116,961  for the three  months  ended
September  30,  1997 as compared  to  $116,761  for the same period in 1996,  an
increase of $200. This increase was due to additional depletion expense,  offset
by declines in production costs, G&A and loss on disposition of assets.

Production  costs were $77,571 for the three months ended September 30, 1997 and
$78,353 for the same period in 1996 resulting in a $782  decrease.  The decrease
was due to lower well maintenance costs.

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,  14% from $5,381 for the three months ended  September
30, 1996 to $4,633 for the same period in 1997.

Depletion was $34,757 for the three months ended  September 30, 1997 compared to
$33,014 for the same period in 1996,  representing an increase of $1,743, or 5%,
primarily  attributable  to a decline in oil reserves during 1997 as a result of
lower commodity prices, offset by a decline in oil production of 651 barrels.

Liquidity and Capital Resources

Net Cash Provided by Operating Activities

Net cash  provided by  operating  activities  increased  $8,127  during the nine
months ended  September 30, 1997 from the same period ended  September 30, 1996.
This increase was  primarily due to a decrease in G&A paid,  offset by a decline
in oil and gas receipts and an increase in production costs paid.

Net Cash Provided by (Used in) Investing Activities

The  Partnership's  investing  activities during the nine months ended September
30, 1997 and 1996 were for  expenditures  related to  equipment  replacement  on
various oil and gas properties.
                                        9





Proceeds from disposition of assets of $6,815 were received from the sale of one
gas well 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 $288,861 of which $2,888 was distributed to the
managing  general  partner and  $285,973 to the limited  partners.  For the same
period ended  September 30, 1996, cash was sufficient for  distributions  to the
partners of $264,111 of which $2,868 was  distributed  to the  managing  general
partner and $261,243 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


                                       10




                           PARKER & PARSLEY 90-A, 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-A, L.P.

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




Dated:  November 6, 1997            By:    /s/ Rich Dealy
                                           ---------------------------------
                                           Rich Dealy, Vice President and
                                             Controller



                                       11