EXHIBIT 5.1









May 21, 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 1,000,000 shares
("Shares") of the Company's Common Stock, no par value per share, which are
reserved for issuance under the Triangle Bancorp, Inc. 1998 Omnibus Stock Plan
(the "Plan"), which Plan was approved by the shareholders of Triangle Bancorp,
Inc. on April 28, 1998.

         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