Exhibit 5
                                                                       ---------

                                April 24, 1995



     MedChem Products, Inc.
     232 West Cummings Park
     Woburn, MA 01801



     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 relating to 1,000,000 shares of the Common Stock, $.01
     par value per share, of MedChem Products, Inc., a Massachusetts corporation
     (the "Company"), issuable under the Company's 1994 Stock Option Plan (the
     "1994 Plan").

          We have examined the Articles of Organization and By-laws of the
     Company, and all amendments thereto, and originals, or copies certified to
     our satisfaction, of all pertinent records of the meetings of the directors
     and stockholders of the Company, the Registration Statement and such other
     documents relating to the Company as we have deemed material for the
     purposes of this opinion.

          In examination of the foregoing documents, we have assumed the
     genuineness of all signatures and 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 latter documents.

          Based upon the foregoing, we are of the opinion that the Company has
     duly authorized for issuance the shares of its Common Stock covered by the
     Registration Statement to be issued under the 1994 Plan, as described in
     the Registration Statement, and such shares, when issued in accordance with
     the terms of the 1994 Plan, will be legally issued, fully paid, and
     nonassessable.

          We hereby consent to the filing of this opinion with the Securities
     and Exchange Commission in connection with the Registration Statement.


                                    Very truly yours,



                                    HALE AND DORR