Joseph P. Gaffigan, 59, a retired executive vice president of the Grady Management Co., a Washington area real estate firm, died Friday at Georgetown University Hospital after a long illness. He suffered from diabetes and complications.

Mr. Gaffigan joined the Grady firm in 1965 as a property manager and was named vice president five years later. He retired in 1977.

He was born in Springfield, Ill. and attended the University of Illinois, leaving school to enter the Navy just prior to World War II.

He was serving as a lieutenant commander aboard the battleship, the U.S. California, at Pearl Harbor when the ship was severely damaged and Mr. Gaffigan was injured. He returned later to active duty and served in the Pacific theater until the war ended.

After the war, Mr. Gaffigan was an [TEXT OMITTED FROM SOURCE] the Illinois Rural Electric News. He came here in 1963 and was manager of the Americana Fairfax, an apartment complex near Annandale, until joining the Grady company.

He was active in the Men's Guild of Holy Cross Hospital and in St. John the Baptist Catholic Church in Silver Spring. He was a member of the Apartment and Office Building Association of Metropolitan Washington.

He is survived by his wife, Anna M., of the home in Silver Spring; three sons, Stephen J. and Joseph F., both of Silver Spring, and Lawrence J., of Highland, Md.; four brothers, Edward, of Springfield , Ill., Walter, of White Plains, N.Y., Patrick, of Willingboro, N.J., and Herb, of Effingham, Ill., and six grandchildren.

A fourth son, Robert M., was killed in 1970 while serving in Vietnam with the U.S. Marines.