June 24, 1997


Securities and Exchange Commission
Judiciary Plaza
450 5th Street, N.W.
Washington, D.C. 20549

         Re:      ADTRAN, Inc. (Commission File No. 0000926282);
                  Registration Statement on Form S-8

Ladies and Gentlemen:

         We have acted as counsel to ADTRAN,  Inc., a Delaware  corporation (the
"Company"),  in connection with the  preparation of a Registration  Statement on
Form  S-8  (the  "Registration  Statement")  and the  filing  thereof  with  the
Securities  and  Exchange  Commission  (the   "Commission").   Pursuant  to  the
Registration Statement, the Company intends to register under the Securities Act
of 1933, as amended,  a total of 2,000,000  shares of Company Common Stock,  par
value $.01 per share (the "Plan Shares") which are issuable upon the exercise of
options which may be granted in the future pursuant to the ADTRAN, Inc. Employee
Incentive Stock Option Plan (the "Plan").

         The opinions  hereinafter  set forth are given to the Commission at the
request of the  Company  pursuant  to Item 8 of Form S-8 and Item  601(b)(5)  of
Regulation  S-K. The only opinion  rendered by this firm consists of the matters
set forth in numbered  paragraph  (1) below (our  "Opinion"),  and no opinion is
implied or to be inferred  beyond  such  matters.  Additionally,  our Opinion is
based upon and subject to the  qualifications,  limitations  and  exceptions set
forth in this letter.

         Our Opinion is furnished for the benefit of the Commission  solely with
regard to the Registration Statement,  may be relied upon by the Commission only
in connection  with the  Registration  Statement and may not otherwise be relied
upon,  used,  quoted or referred to by or filed with any other  person or entity
without our prior written permission.

         In rendering our Opinion, we have examined such agreements,  documents,
instruments  and  records  as we  deemed  necessary  or  appropriate  under  the
circumstances for us to express our Opinion, including,  without limitation, the
Plan.  In making all of our  examinations,  we assumed  the  genuineness  of all
signatures,  the authenticity of all documents submitted to us as originals, the
conformity to the original documents of all documents submitted to us as copies,
and the due  execution  and delivery of all documents by any persons or entities
other than the Company  where due  execution  and  delivery  by such  persons or
entities is a prerequisite to the effectiveness of such documents.

         As to various factual matters that are material to our Opinion, we have
relied upon the factual statements set forth in a certificate of officers of the
Company.  We have not independently  verified or investigated,  nor do we assume
any  responsibility  for, the factual  accuracy or  completeness of such factual
statements.

         The  members  of this  firm  are  admitted  to the Bar of the  State of
Georgia and are duly  qualified to practice law in that state.  We do not herein
express any opinion  concerning  any matter  respecting  or affected by any laws
other than provisions of the General Corporation Law of the State of Delaware as
now in effect and that, in the exercise of reasonable professional judgment, are
normally considered in transactions such as the issuance of the Plan Shares. The
Opinion  hereinafter  set  forth  is based  upon  pertinent  laws  and  facts in
existence as of the date hereof,  and we expressly  disclaim any  obligation  to
advise you of changes to such pertinent laws or facts that hereafter may come to
our attention.

         Based  upon  and  subject  to the  foregoing,  we are of the  following
opinion:

         (1)      the Plan Shares,  when issued in accordance  with the terms of
                  the  Plan  against  payment  in  full  of the  purchase  price
                  therefor set forth in the Plan, will be validly issued,  fully
                  paid and nonassessable.

         We hereby  consent  to the  filing of this  letter as an exhibit to the
Registration Statement.

                                                      Very truly yours,

                                                      LONG ALDRIDGE NORMAN LLP

                                                      By   /s/ Thomas Wardell
                                                           Thomas Wardell