Exhibit 5.1

                        [LETTERHEAD OF LATHAM & WATKINS]


          March 8, 2002


IDEX Corporation
630 Dundee Road
Northbrook, Illinois 60062


            Re:  IDEX Corporation
                 Registration Statement on Form S-3


Ladies and Gentlemen:

            This opinion is rendered in connection with the filing by IDEX
Corporation, a Delaware corporation (the "Company"), of its Registration
Statement on Form S-3 (the "Registration Statement") with the Securities and
Exchange Commission (the "Commission") under the Securities Act of 1933, as
amended (the "Act"), with respect to the offer and sale by the selling
shareholder named in the Registration Statement (the "Offering") of up to
2,939,199 shares of the Company's common stock, par value $.01 per share (the
"Shares"). We have acted as special counsel to the Company in connection with
the preparation of the Registration Statement.

            In our capacity as such counsel, we are generally familiar with the
proceedings taken by the Company in connection with the authorization and
issuance of the Shares. In addition, we have made such legal and factual
examinations and inquiries, including an examination of originals or copies
certified or otherwise identified to our satisfaction of all such documents,
corporate records and instruments, as we have deemed necessary or appropriate
for purposes of this opinion.

            In our examination, we have assumed the legal capacity of all
natural persons, 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 certified or photostatic copies and the
authenticity of the originals of such copies.

            We are opining herein as to the effect on the subject transaction
only of the General Corporation Law of the State of Delaware, and we express no
opinion with respect to the applicability thereto, or the effect thereon, of the
laws of any other jurisdiction or any other Delaware laws, or as to any matters
of municipal law or the laws of any local agencies within any state.

            Subject to the foregoing and the other qualifications set forth
herein, it is our opinion that, as of the date hereof, the Shares have been duly
authorized and validly issued and are fully paid and nonassessable.

            We consent to your filing this opinion as an exhibit to the
Registration Statement and to the reference to our firm under the heading "Legal
Matters" in the Registration Statement.


                                             Very truly yours,

                                             /s/ LATHAM & WATKINS