EXHIBIT 5.1









July 31, 1998






Board of Directors
Triangle Bancorp, Inc.
4300 Glenwood Avenue
Raleigh, NC  27612

RE:   Registration Statement on Form S-8

Ladies and Gentlemen:

      I am a Senior Vice President and General Counsel for Triangle Bancorp,
Inc., a North Carolina corporation (the "Company"), and in such capacity am
familiar with the registration under the Securities Act of 1933, as amended, on
Form S-8 ("Registration Statement") of an aggregate of 200,000 shares ("Shares")
of the Company's Common Stock, no par value per share, which are reserved for
issuance under the Triangle Bancorp, Inc. 1997 Directors Deferred Compensation
(the "Plan).

      As General Counsel of the Company, I have examined the proceedings taken
and am familiar with the proceedings proposed to be taken in connection with the
issuance and sale of the Shares under the Plan. Further, in connection with the
Registration Statement, I have examined the originals or photocopies or
certified copies of such records of the Company, certificates of officers of the
Company and public officials and other documents as I have deemed relevant and
appropriate as the basis for the opinion hereinafter expressed. In such
examination, I have assumed the genuineness of all signatures, the authenticity
of all original documents submitted to me, the conformity to the originals of
all documents submitted to me as certified copies or photocopies and the
authenticity of the originals of such documents.

      Based upon such examination, and relying upon statements of fact contained
in the documents which I have examined, I am of the opinion that the Shares have
been duly and validly authorized and, when issued and sold as contemplated by
the Plan, will be validly issued, fully paid and non-assessable.

      I hereby consent to the filing of this opinion as Exhibit 5.1 to the
Registration Statement.

                                   Very truly yours,



                              /s/ Alexander M. Donaldson
                              -----------------------------------------
                                  Alexander M. Donaldson, Esq.
                                  Senior Vice President and General Counsel

AMD/dmm