EXHIBIT 99.3


                                    FORM OF

                           LYONDELL CHEMICAL COMPANY

                                   LETTER TO
                   THE DEPOSITORY TRUST COMPANY PARTICIPANTS

                                      FOR

                           TENDER OF ALL OUTSTANDING

                          10 7/8% SENIOR SUBORDINATED
                                NOTES DUE 2009
                          IN EXCHANGE FOR REGISTERED
                          10 7/8% SENIOR SUBORDINATED
                                NOTES DUE 2009

THE EXCHANGE OFFER WILL EXPIRE AT 5:00 P.M., NEW YORK CITY TIME, ON
____________, 1999, UNLESS EXTENDED (THE "EXPIRATION DATE"). OUTSTANDING NOTES
TENDERED IN THE EXCHANGE OFFER MAY BE WITHDRAWN AT ANY TIME PRIOR TO 5:00 P.M.,
NEW YORK CITY TIME, ON THE EXPIRATION DATE FOR THE EXCHANGE OFFER.

To Depository Trust Company Participants:

     We are enclosing herewith the materials listed below relating to the offer
by Lyondell Chemical Company (the "Issuer"), Lyondell Chemical Worldwide, Inc.
and Lyondell Chemical Nederland, Ltd. (together, the "Subsidiary Guarantors") to
exchange (the "Exchange Offer") 10 7/8% Senior Subordinated Notes Due 2009 (the
"New Notes"), the issuance of which has been registered under the Securities Act
of 1933, as amended (the "Securities Act"), for a like principal amount of the
issued and outstanding unregistered 10 7/8% Senior Subordinated Notes Due 2009
(the "Outstanding Notes"), upon the terms and subject to the conditions set
forth in the prospectus dated _______________, 1999 (the "Prospectus") and the
related Letter of Transmittal.

     THE ISSUER IS CONCURRENTLY MAKING SEPARATE, INDEPENDENT OFFERS TO EXCHANGE
ITS UNREGISTERED 9 5/8% SENIOR SECURED NOTES, SERIES A, DUE 2007 AND 9 7/8%
SENIOR SECURED NOTES, SERIES B, DUE 2007 FOR A LIKE KIND AND PRINCIPAL AMOUNT OF
ITS REGISTERED 9 5/8% SENIOR SECURED NOTES, SERIES A, DUE 2007 AND 9 7/8% SENIOR
SECURED NOTES, SERIES B, DUE 2007, RESPECTIVELY. PARTICIPANTS IN THE DEPOSITORY
TRUST COMPANY ALSO HOLDING THE ISSUER'S 9 5/8% SENIOR SECURED NOTES, SERIES A,
DUE 2007 AND 9 7/8% SENIOR SECURED NOTES, SERIES B, DUE 2007 WHO WISH TO
PARTICIPATE IN THE SEPARATE, INDEPENDENT EXCHANGE OFFERS RELATING TO SUCH NOTES
WILL NEED TO COMPLETE AND RETURN THE APPLICABLE DOCUMENTATION RELATING TO SUCH
NOTES.

     We are enclosing copies of the following documents:

          1.  Prospectus dated ____________, 1999

          2.  Letter of Transmittal (together with accompanying Substitute Form
              W-9 Guidelines)

          3.  Notice of Guaranteed Delivery

          4.  Letter of instructions that may be sent to your clients for whose
              account you hold Outstanding Notes in your name or in the name of
              your nominee, with space provided for obtaining such client's
              instructions with regard to the Exchange Offer.


     We urge you to contact your clients promptly.  Please note that the
Exchange Offer will expire at 5:00 p.m., New York City time, on ____________,
1999, unless extended.

     The Exchange Offer is not conditioned upon any minimum aggregate principal
amount of Outstanding Notes being tendered for exchange or upon the consummation
of any other Exchange Offer.

     Pursuant to the Letter of Transmittal, each holder of Outstanding Notes
will represent to the Issuer that

     .    any New Notes received are being acquired in the ordinary course of
          business of the person receiving such New Notes;

     .    such person does not have an arrangement or understanding with any
          person to participate in the distribution of the Outstanding Notes or
          the New Notes within the meaning of the Securities Act;

     .    such person is not an "affiliate," as defined in Rule 405 under the
          Securities Act, of the Issuer or a broker-dealer tendering Outstanding
          Notes acquired directly from the Issuer for its own account; and

     .    if such person is not a broker-dealer or is a broker-dealer but will
          not receive New Notes for its own account in exchange for Outstanding
          Notes, it is not engaged in, and does not intend to participate in, a
          distribution of New Notes.

     If such person is a broker-dealer that will receive New Notes for its own
account in exchange for Outstanding Notes, it represents that the Outstanding
Notes to be exchanged for New Notes were acquired as a result of market-making
activities or other trading activities, and it will acknowledge that it will
deliver a Prospectus in connection with any resale of such New Notes; however,
by so acknowledging and by delivering a Prospectus, it will not be deemed to
admit that it is an "underwriter" within the meaning of the Securities Act.

     The enclosed letter to clients contains an authorization by the beneficial
owners of the Outstanding Notes for you to make the foregoing representations.

     The Issuer will not pay any fee or commission to any broker or dealer or to
any other person (other than the Exchange Agent) in connection with the
solicitation of tenders of Outstanding Notes pursuant to the Exchange Offer.
The Issuer will pay or cause to be paid any transfer taxes payable on the
transfer of Outstanding Notes to it, except as otherwise provided in Instruction
7 of the enclosed Letter of Transmittal.

     Additional copies of the enclosed material may be obtained from us.

                                    Very truly yours,

                                    Lyondell Chemical Company




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