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                                                                     EXHIBIT 5.1



June 19, 2001

Sybase, Inc.
6475 Christie Avenue
Emeryville, CA 94608

Re:     Registration Statement on Form S-8 -- Legality of Securities Being
        Registered

Ladies and Gentlemen:

I have examined the Registration Statement on Form S-8 to be filed with the
Securities and Exchange Commission on or about June 19, 2001 (the "Registration
Statement") in connection with the registration under the Securities Act of
1933, as amended, of the following shares of Common Stock of Sybase, Inc.:

        -  4,000,000 shares under the Sybase, Inc. 1996 Stock Plan;

        -  300,000 shares under the Sybase, Inc. 2001 Director Option Plan;

        -  1,342,715 shares under the New Era of Networks, Inc. Amended and
           Restated 1995 Stock Option Plan;

        -  59,242 shares under the New Era of Networks, Inc. Amended and
           Restated 1997 Director Option Plan;

        -  1,382,658 shares under the New Era of Networks, Inc. 1998
           Nonstatutory Stock Option Plan;

        -  5,993 shares under the Century Analysis Inc. 1996 Equity Incentive
           Plan;

        -  4,701 shares under the Convoy Corporation 1997 Stock Option Plan; and

        -  689 shares under the Microscript, Inc. 1997 Stock Option Plan.

Such shares of Common Stock are referred to herein as the "Shares," and such
plans are referred to herein as the "Plans." As counsel in connection with this
transaction, I have examined the proceedings taken and am familiar with the
proceedings proposed to be taken by Sybase in connection with the issuance and
sale of the Shares pursuant to the Plans.

It is my opinion that, when issued and sold in the manner described in the Plans
and pursuant to the agreements which accompany each grant under the Plans, the
Shares will be legally and validly issued, fully-paid and non-assessable.

I consent to the use of this opinion as an exhibit to the Registration
Statement, and further consent to the use of my name wherever appearing in the
Registration Statement and any amendments thereto.

Very truly yours,

/s/ TERESA D. CHUH

Teresa D. Chuh
Vice President and
Associate General Counsel



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