EXHIBIT 5



                                                               February 11, 2002



The Board of Directors


  of MasterCard Incorporated


2000 Purchase Street


Purchase, New York 10577



Ladies and Gentlemen:



     We have acted as counsel to MasterCard Incorporated, a Delaware corporation
(the "Company"), in connection with the Registration Statement on Form S-4 (the
"Registration Statement") filed by the Company with the Securities and Exchange
Commission (the "Commission") under the Securities Act of 1933, as amended (the
"Act"), relating to the issuance by the Company of 84,000,000 shares of Class A
Redeemable Common Stock par value $0.01 per share, and 16,000,000 shares of
Class B Convertible Common Stock par value $0.01 per share (together with any
additional shares of such stock that may be issued by the Company pursuant to
Rule 462(b) (as prescribed by the Commission pursuant to the Act) in connection
with the offering described in the Registration Statement, the "Shares").



     We have examined the Registration Statement and forms of the share
certificates, which have been filed with the Commission as exhibits to the
Registration Statement. We also have examined the originals, or duplicates or
certified or conformed copies, of such records, agreements, instruments and
other documents and have made such other and further investigations as we have
deemed relevant and necessary in connection with the opinions expressed herein.
As to questions of fact material to this opinion, we have relied upon
certificates of public officials and of officers and representatives of the
Company.



     In such examination, we have assumed the genuineness of all signatures, the
legal capacity of natural persons, the authenticity of all documents submitted
to us as originals, the conformity to original documents of all documents
submitted to us as duplicates or certified or conformed copies, and the
authenticity of the originals of such latter documents.



     Based upon the foregoing, and subject to the qualifications and limitations
stated herein, we are of the opinion that when the Board of Directors of the
Company (the "Board") has taken all necessary corporate action to authorize and
approve the issuance of the Shares and upon the satisfaction or waiver of all
conditions to the closing of the conversion and integration transactions
described in the Registration Statement and the subsequent closing of such
transactions, the Shares will be validly issued, fully paid and nonassessable.



     We are members of the Bar of the State of New York and we do not express
any opinion herein concerning any law other than the Delaware General
Corporation Law.



     We hereby consent to the filing of this opinion letter as Exhibit 5 to the
Registration Statement and to the use of our name under the caption "Legal
Matters" in the Prospectus included in the Registration Statement.



                                          Very truly yours,



                                          /s/ SIMPSON THACHER & BARTLETT



                                          SIMPSON THACHER & BARTLETT