WASHINGTON (AP) _ Judge Edward A. Tamm of the U.S. Circuit Court of Appeals for the District of Columbia, a former FBI official, died of cancer Sunday at the age of 79.

Tamm, a native of St. Paul, Minn., came to Washington in 1928 and graduated from Georgetown University law school two years later.

He joined the Federal Bureau of Investigation in 1930, was appointed assistant director in 1934, and served from 1940 to 1948 as assistant to FBI Director J. Edgar Hoover.

He was appointed to the U.S. District Court in 1948 and to the appeals court in 1965.

In a noted 1977 case, Tamm set aside a Federal Communications Commission ruling that seven words, referring to such things as sexual activities and portions of the female anatomy, could not be used by radio stations. He wrote that the FCC order carried the agency into the ''forbidden realm of censorship.''

Tamm attended Mount Saint Charles College in Helena, Mont., and the University of Montana before moving to Washington. He served in the Navy reserve, attaining the rank of lieutenant commander.

In 1945, he was a special adviser to the U.S. delegation to the U.N. Conference on International Organizations.

Survivors include the widow, the former Grace Monica Sullivan of Washington; a son, Edward A. of Amherst, Mass.; a daughter, Grace Escudero of Chevy Chase, Md.; a brother, Quinn Tamm of Kensington, Md., and nine grandchildren.