Exhibit 5.1

         [LETTERHEAD OF JENKENS & GILCHRIST, a Professional Corporation]



                                 August 4, 1999


     Swift Energy Company
     16825 Northchase Drive
     Suite 400
     Houston, Texas 77060

Ladies and Gentlemen:

     We have acted as  securities  counsel  for Swift  Energy  Company,  a Texas
corporation  ("Swift"),  in connection  with (i) the preparation and filing with
the Securities and Exchange  Commission (the "Commission")  under the Securities
Act of 1933, as amended (the "Act"), of Registration  Statement No. 333-81651 on
Form S-3 filed by the Company with the  Commission on June 28, 1999, and amended
and declared effective on July 9, 1999 (the "Registration  Statement"),  for the
purpose of registering under the Act, among other securities, debt securities of
Swift; and (ii) the preparation of a final prospectus  supplement dated July 30,
1999  (the  "Prospectus  Supplement"),   in  connection  with  the  issuance  of
$125,000,000  aggregate principal amount of 10.25% Senior Subordinated Notes Due
2009 of Swift (the "Notes").

     In  connection  with this opinion,  we have  examined  originals or copies,
certified or otherwise  identified to our satisfaction,  of (i) the Registration
Statement,  including the form of prospectus  included therein and the documents
incorporated by reference therein, and the Prospectus  Supplement,  (ii) Swift's
Restated Certificate of Incorporation and By-laws,  each as amended to date, and
(iii) the  Indenture  relating  to Swift debt  securities,  dated as of July 29,
1999, and the form of First Supplemental  Indenture  thereto,  to be dated as of
August 4, 1999 (as so amended and supplemented,  the "Indenture"),  both between
Swift and Bank One, N.A., as trustee. We have also examined originals or copies,
certified or otherwise identified to our satisfaction,  of such other documents,
certificates and records as we have deemed necessary or appropriate, and we have
made such  investigations of law as we have deemed  appropriate,  as a basis for
the opinions expressed below.

     In rendering  the opinions  expressed  below,  we have assumed and have not
verified (i) the  genuineness  of the  signatures on all documents  that we have
examined,  (ii) the conformity to the originals of all documents  supplied to us
as certified or  photostatic  or faxed  copies,  (iii) the  authenticity  of the
originals of such documents and (iv) as to the forms of all documents in respect
of which forms were filed with the  Commission or  incorporated  by reference as







exhibits to the Registration Statement,  the conformity in all material respects
of such documents to the forms thereof that we have examined.  In conducting our
examination of documents  executed by parties other than Swift,  we have assumed
that such parties had the power,  corporate or other,  to enter into and perform
all obligations  thereunder and have also assumed the due  authorization  by all
requisite action, corporate or other, and execution and delivery by such parties
of  such  document  and  that  such  documents   constitute  valid  and  binding
obligations  of such parties.  We have assumed that the Notes and the Indenture,
when executed,  will be executed in  substantially  the forms reviewed by us. In
addition,  we have  assumed  the  receipt by each person to whom a Note is to be
issued (collectively, the "Note Holders") of a certificate for such Note or of a
global  certificate by the Depository  Trust Company,  acting as agent,  and the
payment for the Note so acquired, in accordance with the Registration Statement,
and that the Notes are issued and sold to the Note  Holders in  accordance  with
the Registration  Statement.  As to any facts material to the opinions expressed
herein which were not independently established or verified, we have relied upon
oral or written statements and  representations of officers,  trustees and other
representatives  of the Company and others.  We have  further  assumed  that the
Registration Statement and any amendments thereto have become effective.

     Based upon the foregoing,  and having regard for such legal  considerations
as we deem relevant, we are of the opinion that:

     1.   the Company is a corporation  duly organized,  validly existing and in
          good standing under the laws of the State of Texas;

     2.   when the  Indenture  has  been  duly  executed  and  delivered  by the
          officers  authorized  by the  Board of  Directors  of the  Company  to
          execute and deliver the same,  it will  constitute a legal,  valid and
          binding instrument of the Company,  enforceable against the Company in
          accordance with its terms; and

     3.   the Notes are duly authorized,  and when executed and authenticated in
          the manner  set forth in the  Indenture  and when sold,  issued to and
          paid  for by the  Underwriters,  will  be  legal,  valid  and  binding
          obligations of the Company,  entitled to the benefits  provided by the
          Indenture, and enforceable in accordance with its terms.

     The opinions  expressed above with respect to the legally binding effect of
the Indenture  and the Notes are subject,  as to  enforceability,  to applicable
bankruptcy,  reorganization,  insolvency,  fraudulent  transfer,  moratorium and
other  laws  affecting  creditors'  rights  generally  from  time to time and to
general  principles of equity  (regardless of whether considered in a proceeding
in equity or at law);  commercial  reasonableness and  unconscionability  and an







implied  covenant  of good  faith and fair  dealing;  the power of the courts to
award  damages in lieu of equitable  remedies;  and the  limitations  imposed by
rights to indemnification and contribution  thereunder may be limited by Federal
or state  securities laws or public policy  underlying such laws on any right to
indemnification or contribution contained in the Indenture and the Notes.

     We hereby  consent  to the  filing of this  opinion  as an  exhibit  to the
Registration Statement and to reference being made to our firm under the caption
"Legal  Opinions"  in the  Prospectus  dated July 9, 1999 and under the  caption
"Legal Opinions" in the Prospectus  Supplement dated July 30, 1999, which form a
part of the Registration  Statement.  In giving this consent, this firm does not
thereby  admit  that it comes into the  category  of  persons  whose  consent is
required under Section 7 of the  Securities Act or the rules and  regulations of
the Commission promulgated thereunder.

     We are  members of the Bar of the State of Texas and do not hold  ourselves
out as being  experts  on laws other than the laws of the State of Texas and the
laws of the United States of America.


                                Respectfully submitted,

                                Jenkens & Gilchrist, a Professional Corporation



                                By: /s/ Donald W. Brodsky
                                    --------------------------------------------
                                    Donald W. Brodsky
                                    Authorized Signatory