Joseph D. Guilfoyle, 65, a retired senior attorney in the civil division of the Department of Justice, died of cancer Wednesday at Georgetown University Hospital.

Mr. Guilfoyle joined the antitrust division of Justice shortly after earning his law degree from Georgetown University in 1942. Ten years later, he transferred to the civil division and in 1953 was named second assistant to the assistant attorney general in charge of that division. The assistant attorney general who held that post in those days was Warren E. Burger, now chief justice of the United States.

In 1961, Mr. Guilfoyle became first assistant in the civil division and twice served as acting assistant attorney general in charge of it. He retired in 1969 and then became a legal consultant to various corporations.

Mr. Guilfoyle was born in Victor, Colo., and grew up in St. Mary's, Kan. He earned a bachelor's degree from the University of Missouri in Kansas City in 1938. During his undergraduate days, he also was director of the Boys Division of the Kansas City Court Home and then director of the Mattie Rose Neighborhood Center in Kansas City.

After College, Mr. Guilfoyle moved to Washington and began his law studies at Georgetown. He also worked as a research assistant to Sens. Harry S. Truman and Champ Clark, both Missouri Democrats. In addition, he took some graduate courses at George Washington University in English literature, which remained one of his lifelong interests.

During World War II, he served briefly in the Army and then spent three years in the Navy, including service in the Pacific. He was a lieutenant when he returned to civilian life and resumed his career at Justice.

Mr. Guilfoyle was cited for his legal accomplishments by Georgetown University in 1967.

Survivors include his wife, the former Shirley Simmons, whom he married in 1942, of Washington; two sons, Joseph D. Jr., of Fort Meade, Md., and Patrick S., of Washington, and one sister, Mary Rita Robbins of Washington.

The family suggests that expressions of sympathy be in the form of contributions to the Georgetown University Law Center.