Michael F. Keogh, 77, a Washington lawyer for 50 years, died of congestive heart failure Wednesday at Beebe Hospital in Lewes, Del. He had been at his vacation home at Rehoboth Beach, Del.

Mr. Keogh came to Washington from his native Old Forge, Pa., in 1921. He got a job as a clerk in the U.S. attorney's office and went to Georgetown University Law School, where he graduted in 1928. That year, he was appointed an assistant U.S. attorney and was a prosecutor at the old Police Court for the next five years.

In 1934, he went-into private practice here.

In 1936, Mr Keogh married he former Margaret I. DuFief, of Washington, who survives him.

Mr. Keogh was a member of the board of governors of Georgetown University. He also had served as an adjunct professor at Georgtown. Law School. He was a member of the D.C. Bar.

He also was a member of the Counsellors, the Society of the Friendly Sons of St. Patrick, the University Club, Columbia Country Club and Rehoboth Beach Country Club.

In addition to his wife, of the home in Washington, survivors include three daughters, Mrs. Harry Hull Farr, of Chevy Chase, Katherine Keogh, of Washington, and Adele Corcoran Keogh, of New York City; a brother, lawrence J., of Washington; two sisters, Mrs. George F. Duffy, of Cortland, N.Y., and Mrs. George W. Dolan, of Sarasota, Fla., and four grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to Stone Ridge Country Day School, Bethesda.