Exhibit 23.1



                   CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS


As independent public accountants, we hereby consent to the incorporation of our
report  included  in  this  Form  10-K  into  the  Company's   previously  filed
Registration  Statements  File  Nos.  333-30353,   333-04863,   333-53657,
333-53765, 333-92003, and 333-79151.

                                                ARTHUR ANDERSEN LLP


March 9, 2000
New York, New York

Exhibit 23.1

                         Consent of Independent Auditors

We consent to the  incorporation by reference in the  Registration  Statement on
Form  S-3  (No.  333-92003),  as  amended,  relating  to  KeySpan  Corporation's
registration of $600,000,000 of debt securities,  the Registration  Statement on
Form  S-8  (No.  333-79151),  as  amended,  relating  to  KeySpan  Corporation's
Long-Term Performance Incentive Compensation Plan, the Registration Statement on
Form S-8 (No 333-53765),  relating to KeySpan  Corporation's  Employee  Discount
Stock  Purchase  Plan  and in  the  related  Prospectus,  and  the  Registration
Statement on Form S-3 (No. 333-53657),  relating to the issuance of Common Stock
under KeySpan Corporation's  Investor Program and in the related Prospectus,  of
our report dated May 22,  1998,  with respect to the  financial  statements  and
schedule of Long Island  Lighting  Company  included in the Annual  Report (Form
10-K), of KeySpan Corporation (formerly known as MarketSpan Corporation) for the
year ended December 31, 1999, filed with the Securities and Exchange Commission.

                                                  /S/ERNST & YOUNG LLP

March 9, 2000
Melville, New York