Exhibit 5.1
                        [JENKENS & GILCHRIST LETTERHEAD]




                                 August 19, 1997



Kirby Corporation
1775 St. James Place, Suite 200
Houston, Texas  77056

         Re:  Registration Statement on Form S-8

Gentlemen:

     We have acted as counsel to Kirby  Corporation,  a Nevada  corporation (the
"Company"),  in connection with the  preparation of a Registration  Statement on
Form S-8 (the  "Registration  Statement")  to be filed with the  Securities  and
Exchange  Commission on or about August 19, 1997,  under the  Securities  Act of
1993, as amended (the "Securities Act"),  relating to 900,000 shares of the $.10
par value common  stock (the  "Common  Stock") of the Company that may be issued
upon the exercise of options  granted or that may be granted under 1996 Employee
Stock Option Plan for Kirby Corporation (the "1996 Employee Plan").

     You have  requested  the opinion of this firm with respect to certain legal
aspects of the proposed offering. In connection therewith,  we have examined and
relied upon the original,  or copies identified to our satisfaction,  of (1) the
Restated  Articles  of  Incorporation  and the  Bylaws of the  Company,  each as
amended;  (2) minutes and records of the  corporate  proceedings  of the Company
with respect to the  establishment of the 1996 Employee Plan and the reservation
of 900,000  shares of Common  Stock to be issued  upon the  exercise  of options
granted or to be granted  under the 1996 Employee  Plan (the  "Options")  and to
which the Registration  Statement  relates;  (3) the Registration  Statement and
exhibits thereto, including the 1996 Employee Plan; and (4) such other documents
and  instruments as we have deemed  necessary for the expression of the opinions
herein  contained.  In making the  foregoing  examinations,  we have assumed the
genuineness of all signatures and the authenticity of all documents submitted to
us as  originals,  and the  conformity  to original  documents of all  documents
submitted to us as certified or photostatic  copies.  As to various questions of
fact  material to this  opinion,  and as to the content and form of the Restated
Articles of Incorporation,  the Bylaws, minutes, records,  resolutions and other
documents  or writings of the  Company,  we have  relied,  to the extent we deem
reasonably  appropriate,  upon  representations  or  certificates of officers or
directors of the Company and upon documents,  records and instruments  furnished
to us by the Company,  without independent confirmation or verification of their
accuracy.

CORPDAL:67031.1 13085-00064




Kirby Corporation
August 19, 1997
Page 2


     Based upon our  examination  and  consideration  of, and  reliance  on, the
documents and other  matters  described  above,  and subject to the comments and
exceptions  noted below,  we are of the opinion that the Company  presently  has
available  sufficient  shares of authorized but unissued  shares of Common Stock
from which the 900,000 shares of Common Stock subject to the exercise of Options
may be issued. Furthermore,  assuming that (i) the outstanding Options were duly
granted,  the Options to be granted in the future are duly granted in accordance
with the terms of the 1996  Employee  Plan and the shares of Common  Stock to be
issued  pursuant to the exercise of Options are duly issued in  accordance  with
the terms of the 1996  Employee  Plan,  (ii) the Company  maintains  an adequate
number of authorized but unissued  shares and/or treasury shares of Common Stock
available  for  issuance to those  persons who exercise  Options,  and (iii) the
consideration  for shares of Common  Stock  issued  pursuant to the  exercise of
Options is actually  received by the Company in accordance with the terms of the
1996 Employee Plan and exceeds the par value of such shares,  then we are of the
opinion  that the shares of Common  Stock  issued  pursuant  to the  exercise of
Options and in accordance with the terms of the 1996 Employee Plan, will be duly
and validly issued, fully paid and nonassessable.

     We hereby  consent  to the  filing of this  opinion  as an  exhibit  to the
Registration  Statement and to references to our firm included in or made a part
of the Registration  Statement.  In giving this consent, we do not admit that we
come within the category of person whose consent is required  under Section 7 of
the Securities  Act or the Rules and  Regulations of the Securities and Exchange
Commission thereunder.

                                     Very truly yours,

                                     JENKENS & GILCHRIST,
                                     a Professional Corporation



                                     By: /s/ L. Steven Leshin
                                         -----------------------------
                                         L. Steven Leshin, Authorized Signatory

LSL/ts


CORPDAL:67031.1 13085-00064