Consent of Independent Auditors

We  consent  to the  reference  to our firm under the  caption  "Experts  in the
Registration   Statement  (Form  S-3)  and  related   Prospectus  of  MarketSpan
Corporation for the  registration of 5,000,000 shares of its common stock and to
the  incorporation  by referfence  therein of our report dated January 31, 1997,
with respect to the financial  statements  and schedule of Long Island  Lighting
Company  included in its Annual Report (Form 10-K/A) for the year ended December
31, 1996, filed with the Securities and Exchange Commission.

                                        /s/ Ernst & Young LLP
Melville, New York
May 22, 1998 


May 26, 1998

MarketSpan Corporation
175 East Old Country Road
Hicksville, NY  11801

Gentlemen:

We are aware that MarketSpan  Corporation  has  incorporated by reference in its
current  Registration  Statement on Form S-3, The Brooklyn  Union Gas  Company's
Form 10-Q for the quarters  ended March 31, 1997 and June 30, 1997,  and KeySpan
Energy  Corporation's  Form 10-Q for the  quarters  ended  December 31, 1997 and
March 31, 1998 which  include our reports  dated April 23, 1997,  July 23, 1997,
January  22,  1998 and April 30,  1998,  respectively,  covering  the  unaudited
interim financial information contained therein. Pursuant to Regulation C of the
Securities Act of 1933, our report is not considered a part of the  registration
statement prepared or certified by our firm or a report prepared or certified by
our firm within the meaning of Sections 7 and 11 of the Act.

Very truly yours,

/s/ Arthur Andersen LLP

ARTHUR ANDERSEN LLP