Exhibit 5


                                            January 31, 2006

KeySpan Corporation
One MetroTech Center
Brooklyn, NY 11201

Ladies and Gentlemen:

     I am Executive Vice President and General Counsel of KeySpan Corporation, a
New  York  corporation  (the  "Company").  I have  acted  in  such  capacity  in
connection  with  the  Company's   Registration   Statement  on  Form  S-3  (the
"Registration  Statement")  filed with the  Securities  and Exchange  Commission
under the Securities Act of 1933, as amended,  for the registration of 5,000,000
shares of the  Company's  Common  Stock,  $0.01 par value per share (the "Common
Stock"), issuable pursuant to the KeySpan Investor Program (the "Program").  The
Common Stock  represents  authorized and unissued shares of the Company's Common
Stock.  Where, in this opinion, I refer to actions I have taken, such references
include actions taken by attorneys on my staff and working under my supervision.

     I have  participated  in and am familiar with the corporate  proceedings of
the Company relating to the preparation of the Registration Statement, providing
for the  registration  of the Common Stock for offering and sale on a delayed or
continuous basis under the Act and Rule 415 promulgated thereunder.

     In connection  with the foregoing,  I have researched such questions of law
and examined  the  originals or copies of the  Registration  Statement  and such
corporate  records,  agreements  or other  instruments  of the Company and other
instruments  and documents as I have deemed relevant and necessary in connection
with  the  opinions  hereinafter  expressed.  As to  various  questions  of fact
material to such opinions,  I have, where relevant facts were not  independently
established by me, relied upon statements of other officers of the Company, whom
I believe to be responsible.

     Based upon the foregoing,  and subject to the  assumptions,  qualifications
and limitations set forth herein, it is my opinion that:

,    the Company  has taken all  necessary  corporate  action to  authorize  the
     issuance of the Common Stock;

,    the shares of Common Stock to be issued pursuant to the Program are validly
     authorized  and when issued and delivered in  accordance  with the terms of




     the Program,  the shares of Common Stock so issued will be validly  issued,
     fully paid and non-assessable.

     The  foregoing   opinion  is  delivered  to  you  in  connection  with  the
Registration Statement and may not be relied upon by any other person or for any
other purpose.

     The opinions  expressed above are subject to the qualification  that I am a
member of the Bar of the State of New York and such  opinions are limited to the
laws of the State of New York,  the laws of the United States of America and, to
the extent relevant to the opinion expressed above, the Business Corporation Law
of the State of New York.

     I hereby consent to the reference to me under the caption "Legal  Opinions"
in the Prospectus  included in the  Registration  Statement and to the filing of
this  opinion  as  Exhibit 5 to the  Registration  Statement,  as  amended.  The
foregoing,  however, shall not constitute an admission by me that I am an expert
as provided for in Section 7 and 11 of the Act.

     I wish to call to your attention to the fact that I am the owner of or have
the option to acquire  approximately  142,236  shares of our Common Stock of the
Company.


                                                       Very truly yours,

                                                       /s/ John J. Bishar, Jr.