William E. Dunn, 68, who retired in 1975 as executive vice president of the Associated General Contractors of America, died Monday at his home in Summer, Md. He had suffered from cancer.

Mr. Dunn joined AGCA in 1947. He was named executive director of the group in 1961, a post he held until becoming executive vice president in March 1972.

He had taught labor relations law at Catholic University for the past two years.

Mr. Dunn had served on a number of government panels, including the Missile Sites Labor Commission, the Construction Industry Collective Bargaining Commission and the Citizens Advisory Committee on Transportation Quality.

he was a native of Ohio, Ill. He earned a law degree at DcPaul University in Chicago.

Mr. Dunn practiced law and served as a regional attorney for the Wage Stabilization Board in Chicago during World War II, before moving here in 1947.

He is survived by his wife, Margaret, and a daughter, Suzanne, of the home; another daughter, Mary Virginia Metz, of Ridgewood, N.J. : three sons, James, of Arlington, William F., of Del Norte, Colo., and Roger of San Diego: two brothers, James, of Ohio, Ill., and Raymond J., of Los Alamitos Calif,; two sisters, Mary Cornwall, of Chicago, and Dorothy Kraft, of San Diego, and five grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the William F. Dunn Labor Relations Education Fund at Catholic University.