The Boston Celtics defeated the Atlanta Hawks, 127-118, yesterday afternoon in Atlanta to win the NBA Eastern Division semifinals, 4-2. The Celtics will meet the winner of the New York-Baltimore series--which the Knicks now lead--for the Eastern championships.

Shooting 55 per cent from the floor, the Celts won the final game with Dave Cowens and John Havlicek each throwing in 26 points. The Celtics took the series lead Friday night in Boston, 124-114, behind the 20 point sharpshooting of Steve Kuberski.

The Boston Bruins came from behind with three third-period goals to beat the Toronto Maple Leafs, 5-4, last night and now lead the best-of-seven series, 3-1. Playing at Toronto, the Bruins fell behind 3-1 and 4-2, needing goals by Ken Hodge, Phil Esposito, and John Bucyk to salvage the victory.

The Chicago Black Hawks wrapped up a quick four-game series by defeating the Pittsburgh Penguins, 6-5, in overtime. Chicago meets the winner of the Montreal-New York series which New York now leads, 3-1.

The Bruins meet Toronto again tomorrow night at the Garden in what could be the final game of the series. If the Bruins win the series they will play the winner of the series between the St. Louis Blues and Minnesota North Stars, now knotted at two games apiece. The Blues won, 3-2, in overtime yesterday on home ice.