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                                                                       Exhibit 5

                       [LETTERHEAD OF COZEN AND O'CONNOR]
                                    
                                October 2, 1996     
                                ---------     
Pierce Leahy Corp.
631 Park Avenue
King of Prussia, PA  19406

               Re:    Registration Statement on Form S-4
                      File No. 333-9963
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Ladies and Gentlemen:

               As counsel to Pierce Leahy Corp. (the "Company"), we have
assisted in the preparation of the Company's Registration Statement on Form S-4,
File No. 333-9963 (the "Registration Statement"), filed with the Securities and
Exchange Commission under the Securities Act of 1933, as amended. The
Registration Statement covers $200,000,000 principal amount of the Company's
11-1/8% Senior Subordinated Notes due 2006 (the "Exchange Notes") to be issued
under an Indenture dated as of July 15, 1996 (the "Indenture") between the
Company and United States Trust Company of New York, as trustee (the "Trustee").

               In connection therewith, we have examined the originals or
copies, certified or otherwise identified to our satisfaction, of the Company's
Certificate of Incorporation, its Amended and Restated By-laws, minutes and
resolutions of its Board of Directors and shareholders, the Indenture and such
other documents and corporate records relating to the Company and the issuance
of the Exchange Notes covered by the Registration Statement as we have deemed
necessary or appropriate for purposes of rendering this opinion.

               In our examinations of documents, instruments and other papers,
we have assumed the genuineness of all signatures on original and certified
documents and the conformity to original and certified documents of all copies
submitted to us as conformed, photostatic and other copies. As to matters of
fact which have not been independently established, we have relied upon
representations of officers of the Company.

               Based upon the foregoing examination, information and
assumptions, it is our opinion that upon execution of the Exchange Notes by the
Company, authentication of the Exchange Notes by the Trustee and issuance and
delivery of the Exchange Notes in the manner provided in the Indenture and the
Registration Statement, the Exchange Notes will constitute valid and legally
binding obligations of the Company, enforceable against the Company in
accordance with their terms and entitled to the benefits provided by the
Indenture.
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Pierce Leahy Corp.
    
October 2, 1996      
Page 2

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               The opinion set forth above is subject to the qualification that
the enforceability of the Exchange Notes and the Indenture may be limited by
applicable bankruptcy, insolvency, fraudulent conveyance, moratorium and other
laws affecting the rights of creditors generally and by equitable principles.

               We hereby consent to the reference to our firm in the
Registration Statement under the Prospectus caption "Legal Matters" and to the
inclusion of this opinion as Exhibit 5 to the Registration Statement.

                                                   Very truly yours,



                                                   COZEN AND O'CONNOR
