Exhibit 5(a)
   
                                                               January 14, 1997
    



Board of Directors,
   First Union Corporation,
      Charlotte, North Carolina  28288.

Gentlemen:

                  I am Executive Vice  President,  Secretary and General Counsel
of First Union Corporation,  a North Carolina  corporation (the  "Corporation"),
and am rendering  this opinion in  connection  with the  registration  under the
Securities Act of 1933 (the "Act") of $500,000,000 aggregate principal amount of
Junior  Subordinated  Deferrable  Interest Debentures (the "Debt Securities") of
First Union  Corporation,  a North  Carolina  corporation  (the  "Corporation"),
$500,000,000   aggregate   liquidation   amount   of  Capital   Securities  (the
"Capital Securities")  of  First  Union  Institutional  Capital  I,  a  Delaware
statutory business trust (the "Issuer"), and the Guarantee with respect  to  the
Capital  Securities  (the  "Guarantee")  to  be  executed  and  delivered by the
Corporation  for the benefit of the holders from time to  time  of  the  Capital
Securities.

                  In that connection, I have examined such documents,  corporate
records and other  instruments  as I have deemed  necessary  for the purposes of
this opinion. Based upon the foregoing, I am of the opinion as follows:

                  (1)  The  Corporation  has  been  duly  incorporated  and is a
validly existing corporation under the laws of the State of North Carolina.








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                  (2) When:

                  (i)  the Registration Statement relating to the
         Debt Securities, the Capital Securities and the
         Guarantee has become effective under the Act;

                  (ii)  the Guarantee  Agreement  relating to the Guarantee with
         respect to the Capital Securities of the Issuer has been duly executed
         and delivered;

                  (iii)  the  Debt   Securities  have  been  duly  executed  and
         authenticated in accordance with the Indenture and issued and delivered
         as contemplated in the Registration Statement; and

                  (iv)  the  Capital  Securities  have  been  duly  executed  in
         accordance with the Amended and Restated Trust Agreement of the Issuer
         and issued and delivered as contemplated in the Registration Statement,

the  Debt Securities and the Guarantee relating to the Capital Securities of the
Issuer will constitute valid







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and legally  binding  obligations  of the  Corporation,  subject to  bankruptcy,
insolvency, fraudulent transfer, reorganization,  moratorium and similar laws of
general applicability  relating to or affecting creditors' rights and to general
equity principles.

                  I am  licensed  to  practice  law  only in the  State of North
Carolina.  The foregoing opinion is limited to the Federal laws of the United
States and the laws of the State of North Carolina, and I am expressing no
opinion as to the effect of the laws of any jurisdiction. I have  relied as 
to certain  matters on  information  obtained  from public  officials,  
officers of the Corporation and other sources believed by me to be responsible.

                  I understand that the Corporation has received an opinion
regarding the Capital Securities from Richards, Layton & Finger, LLP, special 
Delaware counsel for the Corporation and the Issuer. I am expressing no opinion
with respect to the matters contained in such opinion.

                  I  hereby  consent  to the use of my name  under  the  heading
"Validity of Securities" in the  Prospectus  forming a part of the  Registration
Statement  and to the use of this  opinion  for  filing  with  the  Registration
Statement as Exhibit 5(a) thereto.  By providing  such  consent,  I do not admit
that I am within the class of persons  whose  consent is required  under Section
7(a) of the Act.

                  Sullivan & Cromwell may rely on this opinion as if
it were addressed to them for purposes of rendering their







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opinion dated the date hereof with respect to the Debt
Securities and the Guarantee.

                                               Very truly yours,



                                              Marion A. Cowell, Jr.