Sugar Ray Leonard of Palmer Park, who is undefeated in three professional boxing bouts, opposes Frankie Santore of Orlando, Fla., today at the Civic Center in Baltimore.

The fight will be televised nationally by the American Broadcasting Co. but will be blacked out in the Washington-Baltimore area. It will be carried on radio by WTOP-1500, beginning at 5:40 p.m.

This will be the first eight-round bout for Leonard, gold medal winner in the welterweight division in the Montreal Olympic Games.

Santore is a veteran of 31 fights, winning 20 of 27 by knockouts, losing three and drawing one. The Marine Corps champion in 1970-71, he has won 11 straight bouts.

Santore is regarded as a hard puncher, having scored nine knockouts in that 11-straight streak. He is a senior at Florida Technical Institute, majoring in psychology.

Leonard scored a technical knockout in the third round of his last bout, against Vinnie DeBarros of Hartford, Conn., June 10.

Three Washington area boxers will be in action in preliminary bouts.

In a 10-round semifinal, middle-weight Leo (Kid) Saenz of Potomac will meet Jimmy Savage of Philadelphia in a rematch. They recently fought to a draw at Capital Centre.

In a six-round heavyweight bout, Charlie (Emperor) Harris of Capitol Heights will oppose Ira Martin of Baltimore.

Odell Leonard, Sugar Ray's cousin, will take on Ronnie Pettigrew of Cleveland in a six-round welterweight fight.

The bouts begin at 4 p.m.