September 15, 2003


GPC Capital Corp. I
Graham Packaging Company, L.P.
Graham Packaging Holdings Company

2401 Pleasant Valley Road
York, Pennsylvania  17402

Ladies and Gentlemen:

         We have acted as counsel to Graham Packaging Company, L.P., a Delaware
limited partnership (the "Operating Company"), and GPC Capital Corp. I, a
Delaware corporation ("CapCo I" and, together with the Operating Company, the
"Issuers") and Graham Packaging Holdings Company, a Pennsylvania limited
partnership (the "Guarantor"), in connection with the Registration Statement on
Form S-4 (the "Registration Statement") filed by the Issuers and the Guarantor
with the Securities and Exchange Commission (the "Commission") under the
Securities Act of 1933, as amended, relating to the issuance by the Issuers of
$100,000,000 aggregate principal amount of 8 3/4% Series B Senior Subordinated
Notes due 2008 (the "Exchange Notes") and the issuance by the Guarantor of a
guarantee (the "Guarantee"), with respect to the Exchange Notes. The Exchange
Notes will be issued under an indenture (the "Indenture"), dated as of February
2, 1998, among the Issuers, the Guarantor and The Bank of New York, as Trustee.
The Exchange Notes will be offered by the Issuers in exchange for $100,000,000
aggregate principal amount of their outstanding 8 3/4% Senior Subordinated Notes
due 2008.

         We have examined the Registration Statement and the Indenture, which
has been filed with the Commission as an exhibit to the Registration Statement.
We also have examined the









                                                           September 15, 2003


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 Issuers and the Guarantor.

         In rendering the opinions set forth below, 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. We also have assumed that the Indenture is the valid and legally
binding obligation of the Trustee.

         Based upon the foregoing, and subject to the qualifications and
limitations stated herein, we are of the opinion that:

         1. When the Exchange Notes have been duly executed, authenticated,
issued and delivered in accordance with the provisions of the Indenture upon the
exchange, the Exchange Notes will constitute valid and legally binding
obligations of the Issuers, enforceable against the Issuers in accordance with
their terms.

         2. When (a) the Exchange Notes have been duly executed, authenticated,
issued and delivered in accordance with the provisions of the Indenture upon the
exchange and (b) the Guarantee has been duly issued, the Guarantee will
constitute a valid and legally binding obligation of the Guarantor enforceable
against the Guarantor, in accordance with its terms.

         Our opinions set forth above are subject to the effects of (1)
bankruptcy, insolvency, fraudulent conveyance, reorganization, moratorium and
other similar laws relating to or affecting creditors' rights generally, (2)
general equitable principles (whether considered in a proceeding in equity or at
law) and (3) an implied covenant of good faith and fair dealing.





                                                           September 15, 2003



         Insofar as the opinions expressed herein relate to or are dependent
upon matters governed by the laws of the Commonwealth of Pennsylvania, we have
relied upon the opinion of Morgan Lewis & Bockius dated the date hereof.

         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 law of the State of
New York, the Federal law of the United States, the Delaware Revised Uniform
Limited Partnership Act and the Delaware General Corporation Law and, to the
extent set forth herein, the laws of the Commonwealth of Pennsylvania.

         We hereby consent to the filing of this opinion letter as Exhibit 5.1
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 LLP
                                            ----------------------------------
                                            SIMPSON THACHER & BARTLETT LLP