<PAGE>
 
                                                                      EXHIBIT 99

                                    FORM OF
                             LETTER OF TRANSMITTAL

                             PLAINS RESOURCES INC.

   Offer to Exchange its 10 1/4% Senior Subordinated Notes due 2006, Series D
                       for any and all of its outstanding
              10 1/4% Senior Subordinated Notes due 2006, Series C


           ---------------------------------------------------------
            THE EXCHANGE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE AT
               5:00 P.M., NEW YORK CITY TIME, ON ________, 1997,
                         UNLESS THE OFFER IS EXTENDED
           ---------------------------------------------------------

              Deliver to Texas Commerce Bank National Association
                             (the "Exchange Agent")

BY REGISTERED OR CERTIFIED MAIL:           BY OVERNIGHT MAIL OR HAND:
Texas Commerce Bank National              Texas Commerce Bank National
       Association                                Association
 Attention: Frank Ivins, Registered Bond  Attention: Frank Ivins, Registered 
  Events, Personal and Confidential                    Bond
       P.O. Box 2320                      Events, Personal and Confidential
  Dallas, Texas  75221-2320                  1201 Main Street, 18th Floor
                                                 Dallas, Texas  75202

                            BY FACSIMILE TRANSMISSION
                        (FOR ELIGIBLE INSTITUTIONS ONLY):
                     Texas Commerce Bank National Association
                                  (214) 672-5746
                             Confirm: (800) 275-2048


     DELIVERY OF THIS INSTRUMENT TO AN ADDRESS OTHER THAN AS SET FORTH ABOVE OR
TRANSMISSION OF INSTRUCTIONS VIA A FACSIMILE NUMBER OTHER THAN THE ONES LISTED
ABOVE WILL NOT CONSTITUTE A VALID DELIVERY.  THE INSTRUCTIONS ACCOMPANYING THIS
LETTER OF TRANSMITTAL SHOULD BE READ CAREFULLY BEFORE THIS LETTER OF TRANSMITTAL
IS COMPLETED.

     The undersigned hereby acknowledges receipt of the Prospectus dated
________, 1997 (the "Prospectus") of Plains Resources Inc. (the "Company") and
this Letter of Transmittal, which together constitute the Company's offer (the
"Exchange Offer") to exchange $1,000 principal amount of its 10 1/4% Senior
Subordinated Notes due 2006, Series D (the "Exchange Notes"), which have been
registered under the Securities Act of 1933, as amended (the "Securities Act"),
pursuant to a Registration Statement of which the Prospectus is a part, for each
$1,000 principal amount of its outstanding 10 1/4% Senior Subordinated Notes due
2006, Series C (the "Notes").  The term "Expiration Date" shall mean 5:00 p.m.,
New York City time, on ________, 1997, unless the Company, in its sole
discretion, extends the Exchange Offer, in which case the term shall mean the
latest date and time to which the Exchange Offer is extended.
<PAGE>
 
Capitalized terms used but not defined herein have the meaning given to them in
the Prospectus.


     YOUR BANK OR BROKER CAN ASSIST YOU IN COMPLETING THIS FORM.  THE
INSTRUCTIONS INCLUDED WITH THIS LETTER OF TRANSMITTAL MUST BE FOLLOWED.
QUESTIONS RELATING TO THE PROCEDURE FOR TENDERING AND REQUESTS FOR ADDITIONAL
COPIES OF THE PROSPECTUS AND THIS LETTER OF TRANSMITTAL MAY BE DIRECTED TO THE
EXCHANGE AGENT.  QUESTIONS RELATING TO THE EXCHANGE OFFER AND REQUESTS FOR
ASSISTANCE OR FOR ADDITIONAL COPIES OF THE PROSPECTUS AND THIS LETTER OF
TRANSMITTAL MAY BE DIRECTED TO THE COMPANY.

     List below the Notes to which this Letter of Transmittal relates.  If the
space indicated below is inadequate, the Certificate Numbers and Principal
amounts should be listed on a separately signed schedule affixed hereto.

<TABLE>
<CAPTION>
=========================================================================================================== 
                              DESCRIPTION OF NOTES TENDERED HEREBY
-----------------------------------------------------------------------------------------------------------
<S>                                                <C>           <C>                  <C>
                                                                    Aggregate Principal            
Name(s) and Address(es) of Registered Holder(s)                            Amount               Principal
 Exactly as Name(s) Appear(s) on Notes             Registration        Represented by            Amount
        (Please fill in)                             Numbers*              Notes                Tendered**
-----------------------------------------------------------------------------------------------------------  
                                                ___________________________________________________________ 
                                                ___________________________________________________________ 
                                                ___________________________________________________________ 
                                                ___________________________________________________________ 
                                                ___________________________________________________________ 
                                                Total
===========================================================================================================
</TABLE>

*  Need not be completed by book-entry Holders.
** Unless otherwise indicated, the holder will be deemed to have tendered the
   full aggregate principal amount represented by such Notes. All tenders must
   be in integral multiples of $1,000.
 
     This Letter of Transmittal is to be used (i) if certificates of Notes are
to be forwarded herewith, (ii) if delivery of Notes is to be made by book-entry
transfer to an account maintained by the Exchange Agent at The Depository Trust
Company ("DTC"), pursuant to the procedures set forth in "The Exchange Offer--
Procedures for Tendering" in the Prospectus or (iii) tender of the Notes is to
be made according to the guaranteed delivery procedures described in the
Prospectus under the caption "The Exchange Offer--Guaranteed Delivery
Procedures."  See Instruction 2.  Delivery of documents to a book-entry transfer
facility does not constitute delivery to the Exchange Agent.  It is understood
that participants in DTC's book-entry system will, in accordance with DTC's
Automated Tender Offer Program procedures and in lieu of physical delivery to
the Exchange Agent of a Letter of Transmittal, electronically acknowledge
receipt of, and agreement to be bound by, the terms of this Letter of
Transmittal.

     The term "Holder" with respect to the Exchange Offer means any person in
whose name Notes are registered on the books of the Company or any other person

                                       2
<PAGE>
 
who has obtained a properly completed bond power from the registered holder. The
undersigned has completed, executed and delivered this Letter of Transmittal to
indicate the action the undersigned desires to take with respect to the Exchange
Offer. Holders who wish to tender their Notes must complete this letter in its
entirety.

[ ]  CHECK HERE IF TENDERED NOTES ARE BEING DELIVERED BY BOOK-ENTRY TRANSFER
     MADE TO AN ACCOUNT MAINTAINED BY THE EXCHANGE AGENT WITH A BOOK ENTRY
     TRANSFER FACILITY AND COMPLETE THE FOLLOWING:

Name of Tendering Institution ________________________________________________

[ ]  The Depository Trust Company

Account Number _______________________________________________________________
Transaction Code Number_______________________________________________________

     Holders whose Notes are not immediately available or who cannot deliver
their Notes and all other documents required hereby to the Exchange Agent on or
prior to the Expiration Date must tender their Notes according to the guaranteed
delivery procedure set forth in the Prospectus under the caption "The Exchange
Offer--Guaranteed Delivery Procedures".  See Instruction 2.

[ ]  CHECK HERE IF TENDERED NOTES ARE BEING DELIVERED PURSUANT TO A NOTICE OF
     GUARANTEED DELIVERY AND COMPLETE THE FOLLOWING:

Name(s) of Registered Holder(s)_______________________________________________
Date of Execution of Notice of Guaranteed Delivery____________________________
Name of Eligible Institution that Guaranteed Delivery_________________________
If delivered by book-entry transfer:
     Account Number___________________________________________________________
     Transaction Code Number__________________________________________________

[ ]  CHECK HERE IF YOU ARE A BROKER-DEALER AND WISH TO RECEIVE 10 ADDITIONAL
     COPIES OF THE PROSPECTUS AND 10 COPIES OF ANY AMENDMENTS OR SUPPLEMENTS
     THERETO.

Name__________________________________________________________________________
Address_______________________________________________________________________

                                       3
<PAGE>
 
                       SIGNATURES MUST BE PROVIDED BELOW
              PLEASE READ THE ACCOMPANYING INSTRUCTIONS CAREFULLY

Ladies and Gentlemen:

          Upon the terms and subject to the conditions of the Exchange Offer,
the undersigned hereby tenders to the Company the principal amount of the Notes
indicated above.  Subject to, and effective upon, the acceptance for exchange of
such Notes tendered hereby, the undersigned hereby exchanges, assigns and
transfers to, or upon the order of, the Company all right, title and interest in
and to such Notes as are being tendered hereby, including all rights to accrued
and unpaid interest thereon as of the Expiration Date.  The undersigned hereby
irrevocably constitutes and appoints the Exchange Agent the true and lawful
agent and attorney-in-fact of the undersigned (with full knowledge that said
Exchange Agent acts as the agent of the Company in connection with the Exchange
Offer) to cause the Notes to be assigned, transferred and exchanged.  The
undersigned represents and warrants that it has full power and authority to
tender, exchange, assign and transfer the Notes and to acquire Exchange Notes
issuable upon the exchange of such tendered Notes, and that when the same are
accepted for exchange, the Company will acquire good and unencumbered title to
the tendered Notes, free and clear of all liens, restrictions, charges and
encumbrances and not subject to any adverse claim.

          The undersigned represents to the Company that (i) the Exchange Notes
acquired pursuant to the Exchange Offer are being obtained in the ordinary
course of business of the person receiving such Exchange Notes, whether or not
such person is the undersigned, and (ii) neither the undersigned nor any such
other person has an arrangement or understanding with any person to participate
in the distribution of such Exchange Notes.  If the undersigned or the person
receiving the Exchange Notes covered hereby is a broker-dealer that is receiving
the Exchange Notes for its own account in exchange for Notes that were acquired
as a result of market-making activities or other trading activities, the
undersigned acknowledges that it or such other person will deliver a prospectus
in connection with any resale of such Exchange Notes.  The undersigned and any
such other person acknowledge that, if they are participating in the Exchange
Offer for the purpose of distributing the Exchange Notes, (i) they cannot rely
on the position of the staff of the Securities and Exchange Commission
enunciated in Exxon Capital Holdings Corporation (available April 13, 1989),
Morgan Stanley & Co., Inc. (available June 5, 1991) or similar no-action letters
and, in the absence of an exemption therefrom, must comply with the registration
and prospectus delivery requirements of the Securities Act in connection with
the resale transaction and (ii) failure to comply with such requirements in such
instance could result in the undersigned or any such other person incurring
liability under the Securities Act for which such persons are not indemnified by
the Company.  If the undersigned or the person receiving the Exchange Notes
covered by this letter is an affiliate (as defined under Rule 405 of the
Securities Act) of the Company, the undersigned represents to the Company that
the undersigned understands and acknowledges that such Exchange Notes may not be
offered for resale, resold or otherwise transferred by the undersigned or such
other person without registration under the Securities Act or an exemption
therefrom.

                                       4
<PAGE>
 
          The undersigned also warrants that it will, upon request, execute and
deliver any additional documents deemed by the Exchange Agent or the Company to
be necessary or desirable to complete the exchange, assignment and transfer of
tendered Notes or transfer ownership of such Notes on the account books
maintained by a Book-Entry Transfer Facility.  The undersigned further agrees
that acceptance of any tendered Notes by the Company and the issuance of
Exchange Notes in exchange therefor shall constitute performance in full by the
Company of its obligations under the Registration Rights Agreement and that the
Company shall have no further obligations or liabilities thereunder for the
registration of the Notes or the Exchange Notes.

          The Exchange Offer is subject to certain conditions set forth in the
Prospectus under the caption "The Exchange Offer -- Conditions."  The
undersigned recognizes that as a result of these conditions (which may be
waived, in whole or in part, by the Company), as more particularly set forth in
the Prospectus, the Company may not be required to exchange any of the Notes
tendered hereby and, in such event, the Notes not exchanged will be returned to
the undersigned at the address shown below the signature of the undersigned.

          All authority herein conferred or agreed to be conferred shall survive
the death or incapacity of the undersigned and every obligation of the
undersigned hereunder shall be binding upon the heirs, personal representatives,
successors and assigns of the undersigned.  Tendered Notes may be withdrawn at
any time prior to the Expiration Date.

          Unless otherwise indicated in the box entitled "Special Registration
Instructions" or the box entitled "Special Delivery Instructions" in this Letter
of Transmittal, certificates for all Exchange Notes delivered in exchange for
tendered Notes, and any Notes delivered herewith but not exchanged, will be
registered in the name of the undersigned and shall be delivered to the
undersigned at the address shown below the signature of the undersigned.  If an
Exchange Note is to be issued to a person other than the person(s) signing this
Letter of Transmittal, or if the Exchange Note is to be mailed to someone other
than the person(s) signing this Letter of Transmittal or to the person(s)
signing this Letter of Transmittal at an address different than the address
shown on this Letter of Transmittal, the appropriate boxes of this Letter of
Transmittal should be completed.  IF NOTES ARE SURRENDERED BY HOLDER(S) THAT
HAVE COMPLETED EITHER THE BOX ENTITLED "SPECIAL REGISTRATION INSTRUCTIONS" OR
THE BOX ENTITLED "SPECIAL DELIVERY INSTRUCTIONS" IN THIS LETTER OF TRANSMITTAL,
SIGNATURE(S) ON THIS LETTER OF TRANSMITTAL MUST BE GUARANTEED BY AN ELIGIBLE
INSTITUTION (SEE INSTRUCTION 4).

                                       5
<PAGE>
 
<TABLE> 
<CAPTION> 
=================================================================================================================================
<S>                                                    <C>  
SPECIAL REGISTRATION INSTRUCTIONS                                             SPECIAL DELIVERY INSTRUCTIONS
      (See Instruction 5)                                                         (See Instruction 5)
 To be completed ONLY if the Exchange Notes are        To be completed ONLY if the Exchange Notes are to be sent to someone other
to be issued in the name of someone other than         than the undersigned, or to the undersigned at an address other than that
the undersigned.                                       shown under "Description of Notes Tendered Hereby."
Issue Exchange Note to:                                Mail Exchange Note to:
Name:___________________________________________       Name:_____________________________________________________________________
Address:________________________________________       Address:__________________________________________________________________
        ________________________________________               __________________________________________________________________
               (Please print or type)                                                   (Please print or type)
================================================================================================================================= 
                                              REGISTERED HOLDER(S) OF NOTES SIGN HERE
                                         (In addition, complete Substitute Form W-9 Below)
 
X________________________________________________________________________________________________________________________________
 
 
X________________________________________________________________________________________________________________________________
                                              (Signature(s) of Registered Holder(s))
        Must be signed by registered holder(s) exactly as name(s) appear(s) on the Notes or on a security position listing as the
owner of the Notes or by person(s) authorized to become registered holder(s) by properly completed bond powers transmitted herewith.
If signature is by attorney-in-fact, trustee, executor, administrator, guardian, officer of a corporation or other person acting in
a fiduciary capacity, please provide the following information (Please print or type): 
Name and Capacity (full title):__________________________________________________________________________________________________

Address (including zip):_________________________________________________________________________________________________________
Area Code and Telephone Number:__________________________________________________________________________________________________
_________________________________________________________________________________________________________________________________
Dated:  ___________________________________
 
                                      Signature Guarantee (If required -- See Instruction 4)
 
Authorized Signature:____________________________________________________________________________________________________________
                                       (Signature of Representative of Signature Guarantor)
 
Name and Title:__________________________________________________________________________________________________________________
 
Name of Firm:____________________________________________________________________________________________________________________
 
Area Code and Telephone Number:__________________________________________________________________________________________________
                                                                    (Please print or type)
Dated:  ___________________________________
==================================================================================================================================
</TABLE>

                                       6
<PAGE>
 
            Payor's Name:  Texas Commerce Bank National Association
             THIS SUBSTITUTE FORM W-9 MUST BE COMPLETED AND SIGNED
     Please provide your social security number or other taxpayer identification
number on the following Substitute Form W-9 and certify therein that you are not
subject to backup withholding.
<TABLE>
<CAPTION>

<S>                             <C>                                                               <C>       
 ==================================================================================================================================
         SUBSTITUTE             Part 1 -- Please provide your TIN in the box at right and 
         FORM W-9               certify by signing and dating below.                              _________________________
 Department of the Treasury                                                                             Social Security
  Internal Revenue Service      Part 2 -- Check the box if you are not subject to backup              Number or Employer
                                withholding under the provisions of section                             Identification        
                                3406(a)(1)(C) of the Internal Revenue Code because                           Number
                                (1) you have not been notified that you are subject 
                                to backup withholding as a result of failure to  
                                report all interest or dividends or (2) the Internal       [ ]
                                Revenue Service has notified you that you are no longer 
                                subject to backup withholding.                                    
                                --------------------------------------------------------------------------------------------------
                                Certification: Under the penalties of perjury, I certify that the 
                                information provided on this form is true, correct and complete.               Part 3-- 
Payor's Request for Taxpayer
Identification Number ("TIN")   Signature:__________________________________  Dated:_____________            AWAITING TIN [ ]
---------------------------------------------------------------------------------------------------------------------------------- 
NOTE:  FAILURE TO COMPLETE AND RETURN THIS FORM MAY RESULT IN BACKUP WITHHOLDING OF 31% OF ANY CASH PAYMENTS IN EXCESS OF $10.00
       MADE TO YOU.

      YOU MUST COMPLETE THE FOLLOWING CERTIFICATE IF YOU CHECKED THE BOX IN PART 3 OF SUBSTITUTE FORM W-9.
----------------------------------------------------------------------------------------------------------------------------------  

                                         CERTIFICATE OF AWAITING TAX IDENTIFICATION NUMBER
 
 I certify under penalties of perjury that a taxpayer identification number has not been issued to me, and either (a) I have mailed
  or delivered an application to receive a taxpayer identification number to the appropriate Internal Revenue Service Center or
  Social Security Administration Office, or (b) I intend to mail or deliver an application in the near future.  I understand that
  if I do not provide a taxpayer identification number within 60 days, 31% of all reportable payments made to me thereafter will be
  withheld until I provide a number.
 
 __________________________________________________________                                     ____________________________________
                   Signature                                                                                    Date
====================================================================================================================================

</TABLE>

                                       7
<PAGE>
 
                                  INSTRUCTIONS

                         FORMING PART OF THE TERMS AND
                        CONDITIONS OF THE EXCHANGE OFFER

1.   DELIVERY OF THIS LETTER OF TRANSMITTAL AND CERTIFICATES.

     All physically delivered Notes or any confirmation of a book-entry transfer
to the Exchange Agent's account at a Book-Entry Transfer Facility of Notes
tendered by book-entry transfer, as well as a properly completed and duly
executed copy of this Letter of Transmittal or facsimile thereof, and any other
documents required by this Letter of Transmittal, must be received by the
Exchange Agent at any of its addresses set forth herein on or prior to the
Expiration Date (as defined in the Prospectus).  THE METHOD OF DELIVERY OF THIS
LETTER OF TRANSMITTAL, THE NOTES AND ANY OTHER REQUIRED DOCUMENTS IS AT THE
ELECTION AND RISK OF THE HOLDER, AND EXCEPT AS OTHERWISE PROVIDED BELOW, THE
DELIVERY WILL BE DEEMED MADE ONLY WHEN ACTUALLY RECEIVED BY THE EXCHANGE AGENT.
IF SUCH DELIVERY IS BY MAIL, IT IS SUGGESTED THAT REGISTERED MAIL WITH RETURN
RECEIPT REQUESTED, PROPERLY INSURED, BE USED.

     No alternative, conditional, irregular or contingent tenders will be
accepted.  All tendering Holders, by execution of this Letter of Transmittal (or
facsimile thereof), shall waive any right to receive notice of the acceptance of
the Notes for exchange.

DELIVERY TO AN ADDRESS OTHER THAN AS SET FORTH HEREIN, OR INSTRUCTIONS VIA A
FACSIMILE NUMBER OTHER THAN THE ONES SET FORTH HEREIN, WILL NOT CONSTITUTE A
VALID DELIVERY.

2.   GUARANTEED DELIVERY PROCEDURES.  Holders who wish to tender their Notes,
but whose Notes are not immediately available and thus cannot deliver their
Notes, the Letter of Transmittal or any other required documents to the Exchange
Agent (or comply with the procedures for book-entry transfer) prior to the
Expiration Date, may effect a tender if:

     (a)  the tender is made through a member firm of a registered national
          securities exchange or of the National Association of Securities
          Dealers, Inc., a commercial bank or trust company having an office or
          correspondent in the United States or an "eligible guarantor
          institution" within the meaning of Rule 17Ad-15 under the Exchange Act
          (an "Eligible Institution");

     (b)  prior to the Expiration Date, the Exchange Agent receives from such
          Eligible Institution a properly completed and duly executed Notice of
          Guaranteed Delivery (by facsimile transmission, mail or hand delivery)
          setting forth the name and address of the Holder, the registration
          number(s) of such Notes and the principal amount of Notes tendered,
          stating that the tender is being made thereby and guaranteeing that,
          within five New York Stock Exchange trading days after the Expiration
          Date, the Letter of Transmittal (or facsimile thereof), together with
          the Notes (or a confirmation of book-entry transfer of such Notes into
          the Exchange Agent's account at the Book-Entry Transfer Facility) and
          any

                                       8
<PAGE>
 
          other documents required by the Letter of Transmittal, will be
          deposited by the Eligible Institution with the Exchange Agent; and

     (c)  such properly completed and executed Letter of Transmittal (or
          facsimile thereof), as well as all tendered Notes in proper form for
          transfer (or a confirmation of book-entry transfer of such Notes into
          the Exchange Agent's account at the Book-Entry Transfer Facility) and
          all other documents required by the Letter of Transmittal, are
          received by the Exchange Agent within five New York Stock Exchange
          trading days after the Expiration Date.

     Upon request to the Exchange Agent, a Notice of Guaranteed Delivery will be
sent to Holders who wish to tender their Notes according to the guaranteed
delivery procedures set forth above.  Any holder who wishes to tender Notes
pursuant to the guaranteed delivery procedures described above must ensure that
the Exchange Agent receives the Notice of Guaranteed Delivery relating to such
Notes prior to the Expiration Date.  Failure to complete the guaranteed delivery
procedures outlined above will not, of itself, affect the validity or effect a
revocation of any Letter of Transmittal form properly completed and executed by
a Holder who attempted to use the guaranteed delivery procedures.

3.   PARTIAL TENDERS; WITHDRAWALS.

     If less than the entire principal amount of Notes evidenced by a submitted
certificate is tendered, the tendering holder should fill in the principal
amount tendered in the column entitled "Principal Amount Tendered" of the box
entitled "Description of Notes Tendered Hereby".  A newly issued Note for the
principal amount of Notes submitted but not tendered will be sent to such holder
as soon as practicable after the Expiration Date.  All Notes delivered to the
Exchange Agent will be deemed to have been tendered in full unless otherwise
indicated.  Tenders of Notes will be accepted only in integral multiples of
$1,000.

     Notes tendered pursuant to the Exchange Offer may be withdrawn at any time
prior to the Expiration Date, after which tenders of Notes are irrevocable.  To
be effective, a written, telegraphic or facsimile transmission notice of
withdrawal must be timely received by the Exchange Agent.  Any such notice of
withdrawal must (i) specify the name of the person having deposited the Notes to
be withdrawn (the "Depositor"), (ii) identify the Notes to be withdrawn
(including the registration number(s) and principal amount of such Notes, or, in
the case of Notes transferred by book-entry transfer, the name and number of the
account at the Book-Entry Transfer Facility to be credited), (iii) be signed by
the Holder in the same manner as the original signature on this Letter of
Transmittal (including any required signature guarantees) or be accompanied by
documents of transfer sufficient to have the Trustee with respect to the Notes
register the transfer of such Notes into the name of the person withdrawing the
tender and (iv) specify the name in which any such Notes are to be registered,
if different from that of the Depositor.  All questions as to the validity, form
and eligibility (including time of receipt) of such notices will be determined
by the Company, whose determination shall be final and binding on all parties.
Any Notes so withdrawn will be deemed not to have been validly tendered for
purposes of the Exchange Offer

                                       9
<PAGE>
 
and no Exchange Notes will be issued with respect thereto unless the Notes so
withdrawn are validly retendered.  Any Notes that have been tendered but not
accepted for exchange, will be returned to the Holder thereof without cost to
such Holder as soon as practicable after withdrawal, rejection of tender or
termination of the Exchange Offer.

4.   SIGNATURE ON THIS LETTER OF TRANSMITTAL; WRITTEN INSTRUMENTS AND
     ENDORSEMENTS; GUARANTEE OF SIGNATURES.

     If this Letter of Transmittal (or facsimile hereof) is signed by the
registered Holder(s) of the Notes tendered hereby, the signature must correspond
with the name(s) as written on the face of the certificates without alteration
or enlargement or any change whatsoever.  If this Letter of Transmittal is
signed by a participant in the Book-Entry Transfer Facility, the signature must
correspond with the name as it appears on the security position listing as the
holder of the Notes.

     If any of the Notes tendered hereby are owned of record by two or more
joint owners, all such owners must sign this Letter of Transmittal.

     If a number of Notes registered in different names are tendered, it will be
necessary to complete, sign and submit as many separate copies of this Letter of
Transmittal as there are different registrations of Notes.

     Signatures on this Letter of Transmittal or a notice of withdrawal, as the
case may be, must be guaranteed by an Eligible Institution unless the Notes
tendered hereby are tendered (i) by a registered Holder who has not completed
the box entitled "Special Registration Instructions" or "Special Delivery
Instructions" on the Letter of Transmittal or (ii) for the account of an
Eligible Institution.

     If this Letter of Transmittal is signed by the registered Holder or Holders
of Notes (which term, for the purposes described herein, shall include a
participant in the Book-Entry Transfer Facility whose name appears on a security
listing as the holder of the Notes) listed and tendered hereby, no endorsements
of the tendered Notes or separate written instruments of transfer or exchange
are required.  In any other case, the registered Holder (or acting Holder) must
either properly endorse the Notes or transmit properly completed bond powers
with this Letter of Transmittal (in either case, executed exactly as the name(s)
of the registered Holder(s) appear(s) on the Notes, and, with respect to a
participant in the Book-Entry Transfer Facility whose name appears on a security
position listing as the owner of Notes, exactly as the name of the participant
appears on such security position listing), with the signature on the Notes or
bond power guaranteed by an Eligible Institution (except where the Notes are
tendered for the account of an Eligible Institution).

     If this Letter of Transmittal, any certificates or separate written
instruments of transfer or exchange are signed by trustees, executors,
administrators, guardians, attorneys-in-fact, officers of corporations or others
acting in a fiduciary or representative capacity, such persons should so
indicate when signing, and, unless waived by the Company, proper evidence
satisfactory to the Company of their authority so to act must be submitted.

                                       10
<PAGE>
 
5.   SPECIAL REGISTRATION AND DELIVERY INSTRUCTIONS.

     Tendering Holders should indicate, in the applicable box, the name and
address (or account at the Book-Entry Transfer Facility) in which the Exchange
Notes or substitute Notes for principal amounts not tendered or not accepted for
exchange are to be issued (or deposited), if different from the names and
addresses or accounts of the person signing this Letter of Transmittal.  In the
case of issuance in a different name, the employer identification number or
social security number of the person named must also be indicated and the
tendering Holder should complete the applicable box.

     If no instructions are given, the Exchange Notes (and any Notes not
tendered or not accepted) will be issued in the name of and sent to the acting
Holder of the Notes or deposited at such Holder's account at the Book-Entry
Transfer Facility.

6.   TRANSFER TAXES.

     The Company shall pay all transfer taxes, if any, applicable to the
transfer and exchange of Notes to it or its order pursuant to the Exchange
Offer.  If a transfer tax is imposed for any other reason other than the
transfer and exchange of Notes to the Company or its order pursuant to the
Exchange Offer, the amount of any such transfer taxes (whether imposed on the
registered Holder or any other person) will be payable by the tendering Holder.
If satisfactory evidence of payment of such taxes or exception therefrom is not
submitted herewith, the amount of such transfer taxes will be billed directly to
such tendering Holder.

     Except as provided in this Instruction 6, it will not be necessary for
transfer stamps to be affixed to the Notes listed in this Letter of Transmittal.

7.   WAIVER OF CONDITIONS.

     The Company reserves the absolute right to waive, in whole or in part, any
of the conditions to the Exchange Offer set forth in the Prospectus.

8.   MUTILATED, LOST, STOLEN OR DESTROYED NOTES.

     Any holder whose Notes have been mutilated, lost, stolen or destroyed
should contact the Exchange Agent at the address indicated above for further
instructions.

9.   REQUESTS FOR ASSISTANCE OR ADDITIONAL COPIES.

     Questions relating to the procedure for tendering as well as requests for
additional copies of the Prospectus and this Letter of Transmittal, may be
directed to the Exchange Agent at the address and telephone number(s) set forth
above.  In addition, all questions relating to the Exchange Offer, as well as
requests for assistance or additional copies of the Prospectus and this Letter
of Transmittal, may be directed to the Company at 1600 Smith Street, Suite 1500,
Houston, Texas  77002, Attention:  Jane Corbett (telephone: (713) 654-1414).

                                       11
<PAGE>
 
10.  VALIDITY AND FORM.

     All questions as to the validity, form, eligibility (including time of
receipt), acceptance of tendered Notes and withdrawal of tendered Notes will be
determined by the Company in its sole discretion, which determination will be
final and binding.  The Company reserves the absolute right to reject any and
all Notes not properly tendered or any Notes the Company's acceptance of which
would, in the opinion of counsel for the Company, be unlawful.  The Company also
reserves the right to waive any defects, irregularities or conditions of tender
as to particular Notes.  The Company's interpretation of the terms and
conditions of the Exchange Offer (including the instructions in this Letter of
Transmittal) will be final and binding on all parties.  Unless waived, any
defects or irregularities in connection with tenders of Notes must be cured
within such time as the Company shall determine.  Although the Company intends
to notify Holders of defects or irregularities with respect to tenders of Notes,
neither the Company, the Exchange Agent nor any other person shall incur any
liability for failure to give such notification.  Tenders of Notes will not be
deemed to have been made until such defects or irregularities have been cured or
waived.  Any Notes received by the Exchange Agent that are not properly tendered
and as to which the defects or irregularities have not been cured or waived will
be returned by the Exchange Agent to the tendering Holders as soon as
practicable following the Expiration Date.


                           IMPORTANT TAX INFORMATION

     Under federal income tax law, a Holder tendering Notes is required to
provide the Exchange Agent with such holder's correct TIN on Substitute Form W-9
below.  If such Holder is an individual, the TIN is the Holder's social security
number.  The Certificate of Awaiting Taxpayer Identification Number should be
completed if the tendering Holder has not been issued a TIN and has applied for
a number or intends to apply for a number in the near future.  If the Exchange
Agent is not provided with the correct TIN, the Holder may be subject to a $50
penalty imposed by the Internal Revenue Service.  In addition, payments that are
made to such Holder with respect to tendered Notes may be subject to backup
withholding.

     Certain Holders (including, among others, all corporations and certain
foreign individuals and foreign entities) are not subject to these backup
withholding and reporting requirements.  In order for such a Holder to qualify
as an exempt recipient, that holder must submit to the Exchange Agent a properly
completed Internal Revenue Service Form W-8, signed under penalties of perjury,
attesting to that Holder's exempt status.  Such forms can be obtained from the
Exchange Agent.

     If backup withholding applies, the Exchange Agent is required to withhold
31% of any amounts otherwise payable to the Holder.  Backup withholding is not
an additional tax.  Rather, the tax liability of persons subject to backup
withholding will be reduced by the amount of tax withheld.  If withholding
results in an overpayment of taxes, a refund may be obtained from the Internal
Revenue Service.

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<PAGE>
 
PURPOSE OF SUBSTITUTE FORM W-9

     To prevent backup withholding on payments that are made to a Holder with
respect to Notes tendered for exchange, the Holder is required to notify the
Exchange Agent of his or her correct TIN by completing the form herein
certifying that the TIN provided on Substitute Form W-9 is correct (or that such
Holder is awaiting a TIN) and that (i) such Holder has not been notified by the
Internal Revenue Service that he or she is subject to backup withholding as a
result of failure to report all interest or dividends or (ii) the Internal
Revenue Service has notified such Holder that he or she is no longer subject to
backup withholding.

WHAT NUMBER TO GIVE THE EXCHANGE AGENT

     Each Holder is required to give the Exchange Agent the social security
number or employer identification number of the record Holder(s) of the Notes.
If Notes are in more than one name or are not in the name of the actual Holder,
consult the instructions on Internal Revenue Service Form W-9, which may be
obtained from the Exchange Agent, for additional guidance on which number to
report.

CERTIFICATE OF AWAITING TAXPAYER IDENTIFICATION NUMBER

     If the tendering holder has not been issued a TIN and has applied for a
number or intends to apply for a number in the near future, write "Applied For"
in the space for the TIN on Substitute Form W-9, sign and date the form and the
Certificate of Awaiting Taxpayer Identification Number and return them to the
Exchange Agent.  If such certificate is completed and the Exchange Agent is not
provided with the TIN within 60 days, the Exchange Agent will withhold 31% of
all payments made thereafter until a TIN is provided to the Exchange Agent.


     IMPORTANT:  THIS LETTER OF TRANSMITTAL OR A MANUALLY SIGNED FACSIMILE
THEREOF (TOGETHER WITH NOTES OR CONFIRMATION OF BOOK-ENTRY TRANSFER AND ALL
OTHER REQUIRED DOCUMENTS) OR A NOTICE OF GUARANTEED DELIVERY MUST BE RECEIVED BY
THE EXCHANGE AGENT ON OR PRIOR TO THE EXPIRATION DATE.

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