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                                                                     EXHIBIT 5.1

April 6, 2000

Saba Software, Inc.
2400 Bridge Parkway
Redwood Shores, CA  94065

Ladies and Gentlemen:

              We have examined the Registration Statement on Form S-8 to be
filed by Saba Software, Inc., a Delaware corporation (the "Company"), with the
Securities and Exchange Commission on April 6, 2000 (the "Registration
Statement"), relating to the registration under the Securities Act of 1933, as
amended, of 14,052,543 shares of the Company's Common Stock, $0.001 par value
(the "Shares"). The Shares are reserved for issuance pursuant to the Company's
1997 Stock Incentive Plan, as amended, and the Company's 2000 Stock Incentive
Plan. As counsel to the Company, we have examined the proceedings taken by the
Company in connection with the registration of the Shares.

              It is our opinion that the Shares, when issued and sold in the
manner described in the Registration Statement and the related Prospectus, will
be legally and validly issued, fully paid and nonassessable.

              We consent to the use of this opinion as an exhibit to the
Registration Statement and further consent to all references to us in the
Registration Statement and any amendments thereto.

                                        Very truly yours,


                                        /s/ Morrison & Foerster LLP