FILED PURSUANT TO RULE 424(B)(3)
                                                       REGISTRATION NO. 33-26185

[Union Carbide Logo]


  Supplement, dated June 9, 2000, to the Prospectus, dated May 2, 1994, for the
     Union Carbide Corporation Dividend Reinvestment and Stock Purchase Plan
                              (Union Carbide DRISP)

Dear Union Carbide DRISP Participant:

         Union Carbide Corporation is looking forward to its planned merger with
The Dow Chemical Company. At this time the merger remains subject to certain
conditions, including review by antitrust regulatory authorities.

         At the effective time of the merger, the Union Carbide DRISP will
terminate and each share of Union Carbide common stock held in the Union Carbide
DRISP will be converted into 1.611 shares of Dow common stock (the same
conversion ratio used for all Union Carbide stock in the merger, adjusted to
reflect a three-for-one split in Dow's common stock declared on May 11, 2000)
and transferred into the Dow Dividend Reinvestment Program ("Dow DRP"). Some of
the provisions of the Union Carbide DRISP and Dow DRP differ. A booklet
describing the terms and conditions of the Dow DRP is enclosed. The Prospectus
for the Union Carbide DRISP has been provided to you previously. You can request
another copy by contacting the Shareholder Services Department at the address,
telephone number or fax number set forth below.

         NO ACTION IS NECESSARY ON YOUR PART IF YOU WISH TO REINVEST YOUR DOW
DIVIDENDS FOLLOWING THE MERGER. AT THE TIME OF THE MERGER YOUR UNION CARBIDE
DRISP ACCOUNT WILL BE CONVERTED AUTOMATICALLY INTO A DOW DRP ACCOUNT.

         If you do not wish to participate in the Dow DRP, you may terminate
your Dow DRP account after the merger in accordance with the terms of the Dow
DRP or you may terminate your Union Carbide DRISP account prior to the merger.
To terminate your Union Carbide DRISP account, you must send Union Carbide a
termination request specifying your election to receive either (a) a stock
certificate for full Union Carbide shares held in your account, plus a check for
the proceeds from the sale of any fractional share, or (b) a check for the
proceeds of the




sale by Union Carbide of all the shares in your account, net of any brokerage
fees or commissions and any applicable transfer tax.

         If you elect to receive a stock certificate as set forth in (a) above
or you are now holding a Union Carbide stock certificate, after the merger takes
place, you will be sent a letter of transmittal to use in surrendering your
Union Carbide stock certificates in exchange for Dow stock certificates. You
should not send in your Union Carbide common stock certificates until you
receive the letter of transmittal.

         If you elect to have Union Carbide sell your shares in accordance with
(b) above, the sale will be made at market, generally within ten (10) business
days after receipt of your request.

         Since the precise date of the merger is not known, if you wish to
terminate your Union Carbide DRISP account you should mail or fax your
termination request promptly to the address or facsimile number set forth below.
If your request is not processed before the merger, your account will be
converted to the Dow DRP. You can then terminate your Dow DRP account as
provided in the enclosed booklet on page 7 under the heading "How do I terminate
my participation in the Dividend Reinvestment Program?".

         UNION CARBIDE IS NO LONGER ACCEPTING OPTIONAL CASH PURCHASES IN THE
UNION CARBIDE DRISP.

         Please address any questions or requests to Union Carbide at:

                                   Union Carbide Corporation
                                   Dividend Reinvestment
                                   Shareholder Services Department, G1
                                   39 Old Ridgebury Road
                                   Danbury, CT 06817-0001

                                   Facsimile No.: 203-794-3357
                                   Telephone No.: 203-794-2212



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