SCHEDULE 14A
                                (RULE 14A-101)

                   INFORMATION REQUIRED IN PROXY STATEMENT

                            SCHEDULE 14A INFORMATION
                PROXY STATEMENT PURSUANT TO SECTION 14(A) OF THE           
                SECURITIES EXCHANGE ACT OF 1934 (AMENDMENT NO. )

Filed by the Registrant [X]

Filed by a Party other than the Registrant [ ]

[ ]  Preliminary Proxy Statement          [ ]  Confidential, for Use of the  
                                               Commission Only (as permitted 
                                               by Rule 14a-6(e)(2))
[ ]  Definitive Proxy Statement

[X]  Definitive Additional Materials

[ ]  Soliciting Material Pursuant to Rule 14a-11(c) or Rule 14a-12

                          UNION CARBIDE CORPORATION
               (Name of Registrant as Specified in Its Charter)


  (Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

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UNION CARBIDE CORPORATION  39 OLD RIDGEBURY ROAD, DANBURY, CT  06817-0001


W. H. JOYCE
CHAIRMAN AND
CHIEF EXECUTIVE OFFICER




                                                  April 13, 1999

Dear Shareholder:

          By now you have received a copy of Union Carbide's 1998 Annual 
Report and the Proxy Statement for the company's annual meeting of 
stockholders to be held on April 28, 1999.  You also may have received a 
letter from State of Wisconsin Investment Board ("SWIB"), the proponent of 
Proposal 3 on this year's agenda.

          YOUR BOARD OF DIRECTORS UNANIMOUSLY OPPOSES PROPOSAL 3 because it 
jeopardizes the Board's ability to maximize shareholder value and is not valid 
under New York law.

          Anyone who makes a hostile attempt to acquire the company will try 
to pay as little as possible.  Shareholders cannot negotiate with the offeror, 
but can only accept or reject an offer.  If our rights plan were to subject 
every bid to a shareholder vote, potential bidders would take advantage of the 
fact that you may feel compelled to vote in favor of a lowball offer, rather 
than letting a potential sale of the company go by.  

          Union Carbide's shareholder rights plan is our most effective 
defense against an unsolicited lowball offer for the company's stock, because 
it requires any bidder to negotiate directly with the Board you elected to 
represent your interests.  The objective of the Board is to get the best 
possible deal for the shareholders. 

          Furthermore, your Board believes that the binding by-law proposed by 
SWIB is invalid under New York law. Based upon the opinion of the company's 
counsel, the language of the law is clear in this regard.  Nevertheless, SWIB 
argues that the law is unsettled because no one has previously challenged the 
company's position in  court.  SWIB says it wants to use your company as a 
test and that it is prepared to meet any legal challenge.  DO NOT LET YOUR 
COMPANY BE A TEST CASE! Since shareholders of Applied Materials, Inc. rejected 
this proposal two weeks ago, SWIB is now focusing on Union Carbide.  Please 
help us avoid the potential for costly, protracted and unnecessary litigation. 
Reject SWIB's threat by defeating this proposal.   

          WE URGE YOU TO VOTE AGAINST PROPOSAL 3.  If you have already voted 
in favor of Proposal 3, we ask you to reconsider.  If you have voted AGAINST, 
we thank you for your support.  

          YOUR VOTE COUNTS.  PLEASE VOTE.  PLEASE VOTE AGAINST PROPOSAL 3.

                                                  Sincerely, 


                                                  /s/ W. H. Joyce
                                                  W. H. Joyce



For additional information, please contact:

William H. Smith            or          D. N. Thold
Shareholder Services                    Investor Relations
(203) 794-3647	                         (203) 794-6448