Nathaniel Stinson, 56, a retired civilian engineer and equal opportunity officer of the Navy Department who was active in civic and veterans organizations, died Saturday at the Washington Hospital Center after a heart attack.

He began his career in the Navy Department in 1951 as a medical engineer with the Naval Ordnance Laboratory in White Oak. From 1966 to 1971 he was a project engineer in the mine warfare division of the Naval Ordnance Systems Command and also a part-time equal employment opportunity coordinator.

Mr. Stinson became equal opportunity coordinator of the Naval Ship Systems Command and a year later was promoted to head of equal employment opportunities and director of the human resources management office of the Naval Material Command. He retired in May 1979.

He received the Defense Department Human Goals Award in 1973 and the Navy Superior Civilian Service Award a year later. Earlier this year he was awarded the Navy's Distinguished Civilian Service Award.

Mr. Stinson was born in Warren, Ohio, and reared in Harrisburg, Pa. During World War II he served in the Army Air Corps, then graduated from an Army specialized training program in basic engineering at Howard University, and fought with the 92nd Infantry Division in the Mediterranean theater.

Following the war, he returned to Howard, where he earned a bachelor's degree in mechanical engineering in 1950.

Mr. Stinson was a founder and was the 1970 president of Prometheans, an organization of 300 former Army engineering students who attended Howard University during World War II.

He was volunteer director of the Prometheans' third annual Career Awareness Fair held this month at the D.C. Armory Starplex. The fair sought to promote career planning in area youth.

Mr. Stinson was a resident of Silver Spring. He was a member of the Allied Civic Group of Montgomery County and the Pigskin Club. He had been president of the Northwest Boundary Civic Association from 1962 to 1964 and served as president of the Tamarack Triangle Civic Association in Colesville in the late 1960s.

Survivors include his wife, Fannie Mae Allen Stinson of Silver Spring; two sons, Dr. Nathaniel Jr., of Denver, and Allan E., of San Franciso; two daughters, Sharyn S. Davis of Silver Spring, and Brends L. Stinson of Port Washington, N.Y.; his mother, Lillian B. Stinson of York, Pa.; three brothers, Reuben, of Harrisburg, Pa., and James B. and Aubrey, both of Washington, and one grandchild.