File 33-57745
                                                                Rule 424(b)(2)/A

PROSPECTUS SUPPLEMENT
(To Prospectus dated September 15, 1999)                       [GRAPHIC OMITTED]



                                1,014,091 Shares

                                   AT&T CORP.

                                  Common Stock
                                   ----------

     This prospectus supplement relates to 1,014,091 shares of our common stock,
par value $1.00 per share,  issued to the  shareholders  of South Chicago Cable,
Inc.,  an  Illinois  corporation  ("South  Chicago"),  in  connection  with  our
acquisition of the outstanding shares of stock of South Chicago. We acquired all
of the  outstanding  shares of South Chicago,  effective  March 21, 2000, for an
aggregate purchase price of $53,936,965.06  through a merger of our wholly owned
subsidiary, South Chicago Acquisition, Inc., an Illinois corporation, into South
Chicago.

     Our common stock is quoted on The New York Stock  Exchange under the symbol
"T." The last  reported  sale  price of the  common  stock on The New York Stock
Exchange on March 17, 2000 was $53 3/16 per share.

     Neither the  Securities and Exchange  Commission  nor any state  securities
commission  has approved or disapproved  of these  securities,  or determined if
this prospectus is truthful or complete. Any representation to the contrary is a
criminal offense.


            The date of this prospectus supplement is March 21, 2000.