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                                                                       EXHIBIT 8

                     [LETTERHEAD OF VINSON & ELKINS L.L.P.]

                                November 1, 2000



Northern Border Partners, L.P.
1400 Smith Street
Houston, Texas  77002

Ladies and Gentlemen:

         We have acted as counsel to Northern Border Partners, L.P. (the
"Partnership") in connection with the Partnership's offering (the "Offering") of
common units representing limited partner interests ("Common Units") in the
Partnership pursuant to the Partnership's Registration Statement on Form S-3
(Registration No. 333-72323) (the "Registration Statement"). In connection
therewith, we have reviewed the discussion (the "Discussion") set forth under
the caption "Tax Considerations" in the Registration Statement, as supplemented
by the discussion set forth under the caption "Recent Tax Developments" in the
Prospectus Supplement filed with the Securities and Exchange Commission pursuant
to Rule 424(b) under the Securities Act of 1933, as amended.

         The Discussion is accurate and complete in all material respects and
constitutes our opinion, which is subject to the assumptions and qualifications
set forth therein, as to the material tax consequences to purchasers of Common
Units pursuant to the Offering. We assume no obligation to update this opinion.

         We hereby consent to the filing of this opinion as an exhibit to a
Current Report on Form 8-K of the Partnership, the incorporation by reference of
this opinion in the Registration Statement and the references to our firm and
this opinion contained in the prospectus supplement forming a part of the
Registration Statement. The issuance of this consent does not concede that we
are an "Expert" for the purposes of the Securities Act of 1933.

                                                       Very truly yours,



                                                       Vinson & Elkins L.L.P.