EXHIBIT 5.1





                                     July 31, 2000


Kirby Corporation
55 Waugh Drive, Suite 1000
Houston, Texas  77007

         Re:      Registration Statement on Form S-8

Gentlemen:

         We have  acted as counsel to Kirby  Corporation,  a Nevada  corporation
(the  "Corporation"),  in connection  with the  preparation of the  Registration
Statement  on Form  S-8 (the  "Registration  Statement")  to be  filed  with the
Securities and Exchange Commission on July 31, 2000, under the Securities Act of
1933, as amended (the "Securities Act"), relating to 100,000 shares of the $0.10
par value  common  stock (the  "Common  Stock") of the  Corporation  that may be
issued upon the exercise of option granted or that may be granted under the 2000
Director Stock Option Plan for Kirby Corporation (the "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  Articles  of  Incorporation  and the Bylaws of the  Corporation,  as
amended; (2) minutes and records of the corporate proceedings of the Corporation
with respect to the  establishment  of the Plan and the  reservation  of 100,000
shares of Common Stock to be issued under the Plan and to which the Registration
Statement  relates;  (3)  the  Registration   Statement  and  exhibits  thereto,
including  the 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  Articles  of  Incorporation,  the Bylaws,
minutes,   records,   resolutions   and  other  documents  or  writings  of  the
Corporation, we have relied, to the extent we deem reasonably appropriate,  upon
representations  or certificates of officers or directors of the Corporation and
upon  documents,  records and  instruments  furnished to us by the  Corporation,
without independent check or verification of their accuracy.

     Based upon our  examination  and  consideration  of, and  reliance  on, the
documents and other matters described above, and subject to the comments and










Kirby Corporation
July 31, 2000
Page 2



assumptions  noted below, we are of the opinion that the  Corporation  presently
has  available at least  100,000  shares of  authorized  but unissued  shares of
Common Stock and/or treasury shares of Common Stock. From these shares of Common
Stock,  the shares of Common  Stock  proposed to be sold through the Plan may be
issued.  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 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 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 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
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 persons 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/ Thomas G. Adler
                                              ----------------------------------
                                              Thomas G. Adler