Exhibit 5.1
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                         [Hale and Dorr LLP letterhead]


                                  June 18, 1999




EIS International, Inc.
555 Herndon Parkway
Herndon, Virginia 20170

     Re:          1998 Stock Incentive Plan --
                  Registration Statement on Form S-8
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Ladies and Gentlemen:

     We have assisted in the preparation of a Registration Statement on Form S-8
(the "Registration Statement") to be filed with the Securities and Exchange
Commission (the "Commission") under the Securities Act of 1933, as amended (the
"Securities Act") relating to 500,000 shares of Common Stock, $0.01 par value
per share (the "Shares"), of EIS International, Inc., a Delaware corporation
(the "Company"), issuable under the Company's 1998 Stock Incentive Plan (the
"Plan").

     We have examined the Restated Certificate of Incorporation and the Amended
and Restated By-Laws of the Company, each as amended to date, the Registration
Statement and originals, or copies certified to our satisfaction, of all
pertinent records of the meetings of the directors and stockholders of the
Company and such other documents relating to the Company as we have deemed
material for the purposes of this opinion.

     In our examination of the foregoing documents, we have assumed the
genuineness of all signatures, the authenticity of all documents submitted to us
as originals, the conformity to original documents of all documents submitted to
us as copies, the authenticity of the originals of such latter documents and the
legal competence of all signatories to such documents.

     We assume that the appropriate action will be taken, prior to the offer and
sale of the Shares to register and qualify the Shares for sale under all
applicable state securities or "blue sky" laws. We express no opinion herein as
the laws of any state or jurisdiction other than the state laws of the
Commonwealth of Massachusetts, the Delaware General Corporation Law and the
federal laws of the United States of America.





     Based upon and subject to the foregoing, we are of the opinion that the
Shares covered by the Registration Statement have been duly authorized for
issuance under the Plan and that the Shares, when issued against payment
therefor in accordance with the terms of the Plan and at a price per share in
excess of the nominal value per share for such Shares, will be validly issued,
fully paid and nonassessable.

     It is understood that this opinion is to be used only in connection with
the offer and sale of the Shares while the Registration Statement is in effect.

     We hereby consent to the filing of this opinion with the Commission as an
exhibit to the Registration Statement in accordance with the requirements of
Item 601(b)(5) of Regulation S-K under the Securities Act and to the use of our
name therein. In giving such consent, we do not hereby admit that we are in the
category of persons whose consent is required under Section 7 of the Securities
Act or the rules and regulations of the Commission.

     Please note that we are opining only as to the matters expressly set forth
herein, and no opinion should be inferred as to any other matter.

                                Very truly yours,

                                /s/ Hale and Dorr LLP

                                Hale and Dorr LLP