[WILMER, CUTLER & PICKERING LETTERHEAD]



                                 June 23, 1998


Donaldson, Lufkin & Jenrette, Inc.
277 Park Avenue
New York, New York 10172

Ladies and Gentlemen:

         We have acted as special counsel in connection with the Company's
Registration Statement on Form S-3, Registration No. 333-34149 (the
"Registration Statement") filed with the Securities and Exchange Commission
pursuant to the Securities Act of 1933, as amended, for the registration of the
sale by Donaldson, Lufkin & Jenrette, Inc. (the "Company") from time to time of
up to $1,000,000,000 aggregate principal amount of senior and subordinated debt
securities (the "Debt Securities"). Pursuant to the Registration Statement, the
Company has filed a Prospectus Supplement dated June 23, 1998, to the
Prospectus dated August 22, 1997, providing for the issuance of Medium Term
Notes due Nine Months or More from Date of Issue (the "Notes") in an aggregate
principal amount of up to $650,000,000.

         We have examined originals or copies, certified or otherwise
identified to our satisfaction, of such documents, corporate records,
certificates of public officials and other instruments as we have deemed
necessary for the purposes of rendering this opinion.

         On the basis of the foregoing, we are of the opinion that:

         The Notes issued pursuant to the Indenture dated September 3, 1997 (as
amended, the "Indenture"), between the Company and the Trustee, have been duly
authorized and, when executed, authenticated, issued and delivered in
accordance with the Indenture and the Distribution Agreement, dated as of
September 3, 1997, as amended as of June 23, 1998 (as





Donaldson, Lufkin & Jenrette, Inc.
June 23, 1998

                                     - 2 -


amended the "Distribution Agreement") such Notes will constitute a valid and
binding obligation of the Company, enforceable in accordance with their terms,
except as (a) the enforceability thereof may be limited by bankruptcy,
insolvency, reorganization, fraudulent transfer, moratorium or similar laws now
or hereinafter in effect relating to or affecting the enforcement of creditors'
rights generally and (b) the availability of equitable remedies may be limited
by equitable principles of general applicability (regardless of whether
considered in a proceeding at law or in equity).

         In connection with the opinion expressed above, we have assumed that
none of the terms of the Notes to be established subsequent to the date hereof
will violate any applicable law or will result in a violation of any provision
of any instrument or agreement then binding upon the Company, or any
restriction imposed by any court or governmental body having jurisdiction over
the Company.

         We are members of the bar of the District of Columbia, New York and
Maryland. The opinions expressed herein concern only the effect of (i) New York
law, (ii) the General Corporation Law of the State of Delaware and (iii)
federal law. Except as expressly noted, we have not considered, and express no
opinion on, the laws of any other jurisdiction.

         We hereby consent to the filing of this opinion as an exhibit to the
Form 8-K which will be filed in connection with the issuance of the Notes.

         This opinion is rendered solely to you in connection with the above
matter. This opinion may not be relied upon by you for any other purpose or
relied upon by or furnished to any other person without our prior written
consent.

                                        Very truly yours,

                                        WILMER, CUTLER & PICKERING


                                        By: /s/ Russell J. Bruemmer
                                           --------------------------------
                                            Russell J. Bruemmer, a partner