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, 2000


                         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 / /






<PAGE>



                        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, 2000 and
               December 31, 1999......................................    3

            Statements of Operations for the three months
              ended March 31, 2000 and 1999...........................    4

            Statement of Partners' Capital for the three months
              ended March 31, 2000....................................    5

            Statements of Cash Flows for the three months
              ended March 31, 2000 and 1999...........................    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

            27.1    Financial Data Schedule

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


                                        2


<PAGE>



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

                          Part I. Financial Information

Item 1.      Financial Statements

                                 BALANCE SHEETS

                                                    March 31,      December 31,
                                                      2000            1999
                                                   -----------     -----------
                                                   (Unaudited)
                 ASSETS

Current assets:
  Cash                                             $   119,312     $   132,031
  Accounts receivable - oil and gas sales              163,541         143,411
                                                    ----------      ----------
        Total current assets                           282,853         275,442
                                                    ----------      ----------
Oil and gas properties - at cost,  based on the
  successful efforts accounting method               9,619,327       9,612,816
Accumulated depletion                               (7,965,809)     (7,939,049)
                                                    ----------      ----------
        Net oil and gas properties                   1,653,518       1,673,767
                                                    ----------      ----------
                                                   $ 1,936,371     $ 1,949,209
                                                    ==========      ==========
LIABILITIES AND PARTNERS' CAPITAL

Current liabilities:
  Accounts payable - affiliate                     $    27,405     $    24,507

Partners' capital:
  Managing general partner                              19,088          19,246
  Limited partners (11,897 interests)                1,889,878       1,905,456
                                                    ----------      ----------
                                                     1,908,966       1,924,702
                                                    ----------      ----------
                                                   $ 1,936,371     $ 1,949,209
                                                    ==========      ==========



  The financial information included as of March 31, 2000 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.

                                        3


<PAGE>



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

                            STATEMENTS OF OPERATIONS
                                   (Unaudited)



                                                        Three months ended
                                                              March 31,
                                                     -------------------------
                                                        2000           1999
                                                     ----------     ----------
Revenues:
  Oil and gas                                        $  330,703     $  153,407
  Interest                                                2,093            939
  Gain on disposition of assets                           2,023            -
                                                      ---------      ---------
                                                        334,819        154,346
                                                      ---------      ---------
Costs and expenses:
  Oil and gas production                                133,608        121,603
  General and administrative                             10,132          5,818
  Depletion                                              26,760         61,543
                                                      ---------      ---------
                                                        170,500        188,964
                                                      ---------      ---------
Net income (loss)                                    $  164,319     $  (34,618)
                                                      =========      =========
Allocation of net income (loss):
  Managing general partner                           $    1,643     $     (346)
                                                      =========      =========
  Limited partners                                   $  162,676     $  (34,272)
                                                      =========      =========
Net income (loss) per limited partnership interest   $    13.67     $    (2.88)
                                                      =========      =========
Distributions per limited partnership interest       $    14.98     $     2.10
                                                      =========      =========



         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.

                                        4


<PAGE>



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

                         STATEMENT OF PARTNERS' CAPITAL
                                   (Unaudited)





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

Balance at January 1, 2000           $   19,246     $1,905,456      $1,924,702

     Distributions                       (1,801)      (178,254)       (180,055)

     Net income                           1,643        162,676         164,319
                                      ---------      ---------       ---------

Balance at March 31, 2000            $   19,088     $1,889,878      $1,908,966
                                      =========      =========       =========



         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.

                                        5


<PAGE>



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

                            STATEMENTS OF CASH FLOWS
                                   (Unaudited)


                                                         Three months ended
                                                               March 31,
                                                      -------------------------
                                                         2000           1999
                                                      ----------     ----------
Cash flows from operating activities:
   Net income (loss)                                  $  164,319     $  (34,618)
   Adjustments to reconcile net income (loss) to net
     cash provided by operating activities:
       Depletion                                          26,760         61,543
       Gain on disposition of assets                      (2,023)           -
   Changes in assets and liabilities:
       Accounts receivable                               (20,130)       (16,624)
       Accounts payable                                    2,898          5,407
                                                       ---------      ---------
           Net cash provided by operating activities     171,824         15,708
                                                       ---------      ---------
Cash flows from investing activities:
   Additions to oil and gas properties                    (6,511)        (4,283)
   Proceeds from asset dispositions                        2,023            -
                                                       ---------      ---------
           Net cash used in investing activities          (4,488)        (4,283)
                                                       ---------      ---------
Cash flows used in financing activities:
   Cash distributions to partners                       (180,055)       (25,254)
                                                       ---------      ---------
Net decrease in cash                                     (12,719)       (13,829)
Cash at beginning of period                              132,031         76,330
                                                       ---------      ---------
Cash at end of period                                 $  119,312     $   62,501
                                                       =========      =========



         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.

                                        6


<PAGE>



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

                          NOTES TO FINANCIAL STATEMENTS
                                 March 31, 2000
                                   (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, 2000 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, 1999 financial  statements to conform to the
March 31, 2000 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, 1999, 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 116% to $330,703 for the three
months ended March 31, 2000 as compared to $153,407 for the same period in 1999.
The increase in revenues resulted from higher average prices received, offset by
a decline in  production.  For the three  months  ended  March 31,  2000,  8,990
barrels of oil, 3,979 barrels of natural gas liquids  ("NGLs") and 15,621 mcf of
gas were  sold,  or 15,573  barrel of oil  equivalents  ("BOEs").  For the three

                                        7


<PAGE>



months ended March 31, 1999,  9,432  barrels of oil,  3,774  barrels of NGLs and
17,569 mcf of gas were sold, or 16,134 BOEs.

The average price  received per barrel of oil increased  $15.94,  or 136%,  from
$11.76 for the three  months  ended March 31, 1999 to $27.70 for the same period
in 2000. The average price received per barrel of NGLs increased $8.49, or 157%,
from  $5.40 for the three  months  ended  March 31,  1999 to $13.89 for the same
period in 2000.  The average  price  received per mcf of gas  increased 33% from
$1.26  during the three months ended March 31, 1999 to $1.68 for the same period
in 2000.  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, 2000.

The volatility of commodity prices has had, and continues to have, a significant
impact on the Partnership's revenues and operating cash flow and could result in
additional  decreases to the  carrying  value of the  Partnership's  oil and gas
properties.

A gain on disposition of assets of $2,023 was recognized during the three months
ended March 31, 2000 from the sale of equipment on one fully depleted well.

Costs and Expenses:

Total costs and expenses  decreased to $170,500 for the three months ended March
31,  2000 as compared  to  $188,964  for the same period in 1999,  a decrease of
$18,464,  or 10%.  The  decrease  was due to a decline in  depletion,  offset by
increases in production costs and general and administrative expenses ("G&A").

Production  costs were  $133,608  for the three  months ended March 31, 2000 and
$121,603 for the same period in 1999,  resulting in a $12,005 increase,  or 10%.
The increase was the result of higher  production taxes due to increased oil and
gas revenues and well maintenance costs incurred to stimulate well production.

G&A's  components are independent  accounting and engineering  fees and managing
general  partner  personnel  and  operating  costs.   During  this  period,  G&A
increased,  in  aggregate,  74% from $5,818 for the three months ended March 31,
1999 to $10,132 for the same period in 2000  primarily  due to increased oil and
gas revenues.

Depletion  was $26,760  for the three  months  ended March 31, 2000  compared to
$61,543 for the same period in 1999, a decrease of $34,783, or 57%. The decrease
was primarily  the result of a combination  of factors that included an increase
in proved  reserves  during the three  months ended March 31, 2000 due to higher
commodity  prices,  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 1999 and a
decline in oil  production  of 442 barrels  for the period  ended March 31, 2000
compared to the same period in 1999.

                                        8


<PAGE>




Liquidity and Capital Resources

Net Cash Provided by Operating Activities

Net cash provided by operating  activities  increased  $156,116 during the three
months  ended  March 31,  2000 from the same period in 1999.  The  increase  was
primarily attributable to an increase of $174,944 in oil and gas sales receipts,
offset by increases in operating  costs paid of $15,631 and in G&A expenses paid
of $3,197.

Net Cash Used in Investing Activities

The  Partnership's  principal  investing  activities  for the three months ended
March 31, 2000 and 1999 were related to  expenditures  for oil and gas equipment
on active properties.

Proceeds  from asset  dispositions  of $2,023  received  during the three months
ended  March  31,  2000 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, 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.  For the same period ended March 31, 1999,
cash  distributions to the partners were $25,254,  of which $252 was distributed
to the managing general partner and $25,002 to the limited partners.

Other Items

Year 2000

During 1998, the managing general partner established a "Year 2000" project that
assessed the Partnership's and the managing general partner's internal Year 2000
problem; took remedial actions necessary to minimize the Year 2000 risk exposure
to the managing  general  partner and third  parties;  and,  tested the managing
general partner's systems and processes once remedial actions were taken.

The  managing  general  partner  has  closely   monitored  its  information  and
non-information   technology  systems  since  the  beginning  of  2000  and  has
identified no significant Year 2000 failures or problems.

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

(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

         27.1   Financial Data Schedule

(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 9, 2000           By:      /s/ Rich Dealy
                                       -------------------------------
                                       Rich Dealy, Vice President
                                         and Chief Accounting Officer

                                       11


<PAGE>