Dominick L. (Dom) Manoli, 74, who retired in 1971 as an associate general counsel of the National Labor Relations Board, died Wednesday at George Washington University Hospital. He had a heart ailment.

He joined the NLRB as an attorney in Washington in 1941, serving in the division of enforcement litigation, which dealt with obtaining federal court enforcement of board orders in unfair labor practice cases.

Mr. Manoli became a supervisory attorney in 1945, assistant general counsel in charge of Supreme Court litigations in 1953, and then associate general counsel in charge of the litigation division in 1960.

Some of the landmark cases that he argued before the Supreme Court involved the legality of some lockouts, the scope of mandatory collective bargaining and the validity of "hot cargo" agreements between emloyers and unions.

Mr. Manoli was born in Lentini, Italy, and reared in Omaha, Neb. He graduated from Harvard College and Harvard Law School and had a private law practice before joining the NLRB. He lived in Arlington.

His first wife, Dorothy Manoli, died in 1973.

He is survived by his wife, Olive, of Arlington; four stepchildren, Kathryn, Richard, Rodger and Robert Louie, all of Arlington; a brother, Robert, of Huntington Beach, Calif., and three sisters, Nellie Manoli, Diane Drummond and Helen Pascale, all of Omaha.