EXHIBITS 5 AND 23(A)
 
                                          May 8, 1996
 
Interleaf, Inc.
Prospect Place
9 Hillside Avenue
Waltham, MA 02154
 
Gentlemen:
 
    I  have assisted in the preparation of  a Registration Statement on Form S-3
to be  filed with  the  Securities and  Exchange Commission  (the  "Registration
Statement"),  relating to  450,000 shares  of Common  Stock, $.01  par value per
share (the  "Shares"),  of Interleaf,  Inc.,  a Massachusetts  corporation  (the
"Company"),  issuable to David  and Lisa Allman,  and Lee Fields,  pursuant to a
certain agreement with the Company ("Agreement").
 
    I have examined (i) the Restated Articles of Organization and By-laws of the
Company and all amendments thereto, (ii)  the Agreement, and (iii) such  records
of  meetings of  the directors  and stockholders  of the  Company, documents and
other instruments as in my judgement  are necessary or appropriate to enable  me
to render the opinion expressed below.
 
    In my examination of the foregoing documents, I have assumed the genuineness
of  all signatures  and the  authenticity of  all documents  submitted to  me as
originals, the conformity to original documents of all documents submitted to me
as certified or  photostatic copies, and  the authenticity of  the originals  of
such latter documents.
 
    Based upon the foregoing, I am of the opinion that the Shares have been duly
authorized  for issuance and,  when issued in  accordance with the  terms of the
Agreement against  payment therefor,  will  be legally  issued, fully  paid  and
nonassessable.
 
    I  hereby consent to  the use of  my name in  the Registration Statement and
consent to  the  filing  of  this  opinion  with  the  Securities  and  Exchange
Commission as an exhibit to the Registration Statement.
 
                                          Very truly yours,
 
                                                    /s/ JOHN K. HYVNAR
 
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                                                   John K. Hyvnar, Esq.
                                                     GENERAL COUNSEL