1

                       OPINION OF VINSON & ELKINS L.L.P.

                                                                       EXHIBIT 8

                                 JUNE 21, 2001

NORTHERN BORDER PARTNERS, L.P.
1400 SMITH STREET
HOUSTON, TEXAS 77002

Gentlemen:

     We have acted as counsel to Northern Border Partners, L.P., a Delaware
limited partnership (the "Partnership"), in connection with the registration of
5,711,901 units representing limited partner interests in the Partnership (the
"common units") on behalf of certain offering unitholders pursuant to the
Registration Statement on Form S-3 (the "Registration Statement") to be filed
with the SEC under the Securities Act of 1933. In connection therewith, we
prepared the discussion set forth under the caption "Tax Considerations" in the
Registration Statement (the "Discussion"). Capitalized terms not defined herein
shall have the meanings ascribed to them in the Amended and Restated Agreement
of Limited Partnership of Northern Border Partners, L.P. (the "Partnership
Agreement").

     All statements of legal conclusions contained in the Discussion, unless
otherwise noted, reflect our opinion with respect to the matters set forth
therein as of the effective date of the Registration Statement. In addition, we
are of the opinion that the federal income tax discussion in the Registration
Statement with respect to those matters as to which no legal conclusions are
provided is an accurate discussion of such federal income tax matters (except
for the representations and statements of fact of the Partnership and its
general partners, included in such discussion, as to which we express no
opinion).

     We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the use of our name in the Registration Statement.
This consent does not constitute an admission that we are "experts" within the
meaning of such term as used in the Securities Act of 1933.

                                            Very truly yours,

                                            /s/ VINSON & ELKINS L.L.P.
                                            Vinson & Elkins L.L.P.