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


                                    FORM 10-Q


                Quarterly Report Pursuant to Section 13 or 15(d)
                     of the Securities Exchange Act of 1934

                  For the quarterly period ended March 31, 2001


                         Commission File No. 33-26097-08


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

                        Delaware                            75-2329284
            ---------------------------------         ---------------------
             (State or other jurisdiction of             (I.R.S. Employer
             incorporation or organization)           Identification Number)


1400 Williams Square West, 5205 N. O'Connor Blvd., Irving, Texas     75039
----------------------------------------------------------------   ---------
           (Address of principal executive offices)                (Zip code)


       Registrant's Telephone Number, including area code : (972) 444-9001

                                 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 / /






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

                                TABLE OF CONTENTS


                                                                        Page
                          Part I. Financial Information

Item 1.     Financial Statements

            Balance Sheets as of March 31, 2001 and
               December 31, 2000.....................................    3

            Statements of Operations for the three months
              ended March 31, 2001 and 2000..........................    4

            Statement of Partners' Capital for the three months
              ended March 31, 2001...................................    5

            Statements of Cash Flows for the three months
              ended March 31, 2001 and 2000..........................    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

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


                                        2

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

                          Part I. Financial Information

Item 1.      Financial Statements
<TABLE>

                                 BALANCE SHEETS

                                                      March 31,     December 31,
                                                        2001            2000
                                                     -----------    -----------
                                                     (Unaudited)
                 ASSETS

<S>                                                  <C>            <C>
Current assets:
  Cash                                               $   131,173    $   132,300
  Accounts receivable - oil and gas sales                210,919        209,552
                                                      ----------     ----------
        Total current assets                             342,092        341,852
                                                      ----------     ----------
Oil and gas properties - at cost,  based on the
  successful efforts accounting method                 9,628,428      9,628,120
Accumulated depletion                                 (8,102,672)    (8,075,752)
                                                      ----------     ----------
        Net oil and gas properties                     1,525,756      1,552,368
                                                      ----------     ----------
                                                     $ 1,867,848    $ 1,894,220
                                                      ==========     ==========
LIABILITIES AND PARTNERS' CAPITAL

Current liabilities:
  Accounts payable - affiliate                       $    28,900    $    15,580

Partners' capital:
  Managing general partner                                18,388         18,785
  Limited partners (11,897 interests)                  1,820,560      1,859,855
                                                      ----------     ----------
                                                       1,838,948      1,878,640
                                                      ----------     ----------
                                                     $ 1,867,848    $ 1,894,220
                                                      ==========     ==========



  The financial information included as of March 31, 2001 has been prepared by
  the managing general partner without audit by independent public accountants.

   The accompanying notes are an integral part of these financial statements.
</TABLE>

                                        3

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

                            STATEMENTS OF OPERATIONS
                                   (Unaudited)


<TABLE>


                                                        Three months ended
                                                             March 31,
                                                     -------------------------
                                                        2001           2000
                                                     ----------     ----------

<S>                                                  <C>            <C>
Revenues:
  Oil and gas                                        $  424,735     $  330,703
  Interest                                                2,507          2,093
  Gain on disposition of assets                           1,975          2,023
                                                      ---------      ---------
                                                        429,217        334,819
                                                      ---------      ---------
Costs and expenses:
  Oil and gas production                                143,206        133,608
  General and administrative                             13,562         10,132
  Depletion                                              26,920         26,760
                                                      ---------      ---------
                                                        183,688        170,500
                                                      ---------      ---------
Net income                                           $  245,529     $  164,319
                                                      =========      =========
Allocation of net income:
  Managing general partner                           $    2,455     $    1,643
                                                      =========      =========
  Limited partners                                   $  243,074     $  162,676
                                                      =========      =========
Net income per limited partnership interest          $    20.43     $    13.67
                                                      =========      =========



         The financial information included herein has been prepared by
  the managing general partner without audit by independent public accountants.

   The accompanying notes are an integral part of these financial statements.
</TABLE>

                                        4

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

                         STATEMENT OF PARTNERS' CAPITAL
                                   (Unaudited)



<TABLE>


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


<S>                                    <C>           <C>            <C>
Balance at January 1, 2001             $   18,785    $ 1,859,855    $1,878,640

     Distributions                         (2,852)      (282,369)     (285,221)

     Net income                             2,455        243,074       245,529
                                        ---------      ---------     ---------

Balance at March 31, 2001              $   18,388    $ 1,820,560    $1,838,948
                                        =========     ==========     =========






         The financial information included herein has been prepared by
  the managing general partner without audit by independent public accountants.

   The accompanying notes are an integral part of these financial statements.
</TABLE>

                                        5

<PAGE>



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

                            STATEMENTS OF CASH FLOWS
                                   (Unaudited)


<TABLE>


                                                             Three months ended
                                                                  March 31,
                                                          -------------------------
                                                             2001          2000
                                                          ----------     ----------
<S>                                                       <C>            <C>
Cash flows from operating activities:
   Net income                                             $  245,529     $  164,319
   Adjustments to reconcile net income to net
     cash provided by operating activities:
       Depletion                                              26,920         26,760
       Gain on disposition of assets                          (1,975)        (2,023)
   Changes in assets and liabilities:
       Accounts receivable                                    (1,367)       (20,130)
       Accounts payable                                       13,320          2,898
                                                           ---------      ---------
           Net cash provided by operating activities         282,427        171,824
                                                           ---------      ---------
Cash flows from investing activities:
   Additions to oil and gas properties                          (308)        (6,511)
   Proceeds from disposition of assets                         1,975          2,023
                                                           ---------      ---------
           Net cash provided by (used in) investing
             activities                                        1,667         (4,488)
                                                           ---------      ---------
Cash flows used in financing activities:
   Cash distributions to partners                           (285,221)      (180,055)
                                                           ---------      ---------
Net decrease in cash                                          (1,127)       (12,719)
Cash at beginning of period                                  132,300        132,031
                                                           ---------      ---------
Cash at end of period                                     $  131,173     $  119,312
                                                           =========      =========




         The financial information included herein has been prepared by
  the managing general partner without audit by independent public accountants.

   The accompanying notes are an integral part of these financial statements.
</TABLE>

                                        6

<PAGE>



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

                          NOTES TO FINANCIAL STATEMENTS
                                 March 31, 2001
                                   (Unaudited)

Note 1.     Organization and nature of operations

Parker & Parsley 90-B Conv., L.P. (the "Partnership") was organized as a general
partnership  in 1990 under the laws of the State of Texas and was converted to a
Delaware limited partnership on August 1, 1991.

The  Partnership  engages in oil and gas development and production in Texas and
is not involved in any industry segment other than oil and gas.

Note 2.     Basis of presentation

In  the  opinion  of  management,  the  unaudited  financial  statements  of the
Partnership as of March 31, 2001 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
may have been made to the March 31, 2000 financial  statements to conform to the
March 31, 2001 financial statement presentations.

Certain  information  and footnote  disclosures  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, 2000, as filed with the Securities and Exchange Commission,  a copy
of which is available upon request by writing to Rich Dealy,  Vice President and
Chief Accounting Officer,  5205 North O'Connor  Boulevard,  1400 Williams Square
West, Irving, Texas 75039-3746.

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

Results of Operations

Revenues:

The Partnership's  oil and gas revenues  increased 28% to $424,735 for the three
months ended March 31, 2001 as compared to $330,703 for the same period in 2000.
The increase in revenues resulted from higher average prices received, offset by
a decline in  production.  For the three  months  ended  March 31,  2001,  8,755
barrels of oil, 3,239 barrels of natural gas liquids  ("NGLs") and 18,996 mcf of
gas were  sold,  or 15,160  barrel of oil  equivalents  ("BOEs").  For the three
months ended March 31, 2000,  8,990  barrels of oil,  3,979  barrels of NGLs and
15,621 mcf of gas were sold, or 15,573 BOEs.

                                        7

<PAGE>



The average price received per barrel of oil increased $1.56, or 6%, from $27.70
for the three months ended March 31, 2000 to $29.26 for the same period in 2001.
The average  price  received per barrel of NGLs  increased  $4.36,  or 31%, from
$13.89 for the three  months  ended March 31, 2000 to $18.25 for the same period
in 2001.  The average price  received per mcf of gas  increased  243% from $1.68
during the three  months  ended  March 31,  2000 to $5.76 for the same period in
2001. 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 three
months ended March 31, 2001.

Gains on disposition  of assets of $1,975 and $2,023 was  recognized  during the
three  months  ended  March 31,  2001 and 2000,  respectively,  from the sale of
equipment on one fully depleted well.

Costs and Expenses:

Total costs and expenses  increased to $183,688 for the three months ended March
31, 2001 as compared  to  $170,500  for the same period in 2000,  an increase of
$13,188,  or 8%. The  increase  was due to  increases  in  production  costs and
general, administrative expenses ("G&A") and depletion.

Production  costs were  $143,206  for the three  months ended March 31, 2001 and
$133,608 for the same period in 2000, resulting in a $9,598 increase, or 7%. The
increase was primarily due to higher production taxes associated with higher oil
and gas prices.

G&A's  components are independent  accounting and engineering  fees and managing
general partner  personnel and  administrative  costs.  During this period,  G&A
increased  34% from $10,132 for the three months ended March 31, 2000 to $13,562
for the  same  period  in 2001,  primarily  due to a  higher  percentage  of the
managing  general  partner's G&A being  allocated  (limited to 3% of oil and gas
revenues) as a result of  increased  oil and gas revenues and an increase in the
accrual for tax preparation fees.

Depletion  was $26,920 for the three  months ended March 31, 2001 as compared to
$26,760 for the same  period in 2000,  an increase  of $160.  The  increase  was
primarily due to downward  revisions to proved  reserves on several wells during
the  three  months  ended  March  31,  2001,   offset  by  a  reduction  in  the
Partnership's  net  depletable  basis  from  charges  taken in  accordance  with
Statement  of  Financial  Accounting  Standards  No.  121,  "Accounting  for the
Impairment of  Long-Lived  Assets and for  Long-Lived  Assets to be Disposed Of"
("SFAS 121") during the fourth  quarter of 2000 and a decline in oil  production
of 235 barrels for the period  ended March 31, 2001  compared to the same period
in 2000.

Liquidity and Capital Resources

Net Cash Provided by Operating Activities

Net cash provided by operating  activities  increased  $110,603 during the three
months  ended  March 31,  2001 from the same period in 2000.  The  increase  was
primarily  attributable  to an increase of $94,446 in oil and gas sales receipts
and a reduction in working capital of $29,185, offset by increases in production
costs of $9,598 and G&A expenses of $3,430. The increase in oil and gas receipts
resulted from the increase in commodity prices during 2001 which  contributed an

                                        8

<PAGE>



additional  $95,426 to oil and gas receipts,  offset by $980  resulting from the
decline in  production  during 2001 as compared to the same period in 2000.  The
increase in production  costs was primarily  due to increased  production  taxes
associated with higher oil and gas prices. The increase in G&A was primarily due
to a higher  percentage of the managing  general  partner's G&A being  allocated
(limited to 3% of oil and gas  revenues)  as a result of  increased  oil and gas
revenues and an increase in the accrual for tax preparation fees.

Net Cash Provided by (Used in) Investing Activities

The  Partnership's  principal  investing  activities  for the three months ended
March 31, 2001 and 2000 were for  expenditures  related to oil and gas equipment
upgrades on active properties.

Proceeds from  disposition  of assets of $1,975 and $2,023  received  during the
three months ended March 31, 2001 and 2000, respectively,  were derived from the
sale of equipment on one fully depleted well.

Net Cash Used in Financing Activities

For the three months ended March 31, 2001,  cash  distributions  to the partners
were $285,221,  of which $2,852 was distributed to the managing  general partner
and $282,369 to the limited partners.  For the same period ended March 31, 2000,
cash  distributions  to  the  partners  were  $180,055,   of  which  $1,801  was
distributed  to the  managing  general  partner  and  $178,254  to  the  limited
partners.

Proposal to acquire partnerships

On April  17,  2001,  Pioneer  Natural  Resources  Company  ("Pioneer")  filed a
preliminary  proxy   statement/prospectus   with  the  Securities  and  Exchange
Commission  proposing an agreement  and plan of merger  among  Pioneer,  Pioneer
Natural  Resources  USA, Inc.  ("Pioneer  USA"),  a wholly- owned  subsidiary of
Pioneer,  and the limited partners of 46 Parker & Parsley limited  partnerships.
Each  partnership  that  approves the agreement and plan of merger and the other
related  merger  proposals  will  merge  with  and  into  Pioneer  USA,  and the
partnership  interests of each such partnership will be converted into the right
to receive cash and Pioneer  common  stock.  Pioneer USA is the sole or managing
general partner of the  partnerships.  The Partnership is one of the 46 Parker &
Parsley limited  partnerships  being requested to approve the agreement and plan
of merger.  The  preliminary  proxy  statement/prospectus  is non-binding and is
subject to, among other  things,  consideration  of offers from third parties to
purchase any  partnership  or its assets,  the majority  approval of the limited
partnership  interests in each  partnership and the resolution of Securities and
Exchange  Commission  review  comments.  No  solicitation  will  be  made  using
preliminary materials.

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

(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.

                                        9

<PAGE>



                           Part II. Other Information


Item 6.     Exhibits and Reports on Form 8-K

(a)      Exhibits - none

(b)      Reports on Form 8-K - none.


                                       10

<PAGE>


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


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



Dated:  May 11, 2001              By:      /s/ Rich Dealy
                                           -----------------------------------
                                           Rich Dealy, Vice President
                                             and Chief Accounting Officer



                                       11

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