Frederick M. Bradley, 78, a senior partner in the law firm of Hogan and Hartson until his retirement four years ago, died Friday at Georgetown University Hospital after a heart attack. He lived in Washington, where he had been active in civic affairs.

Mr. Bradley was born in Georgetown. A graduate of Western High School, he earned a degree in 1923 from the George Washington University Law School. He had his own law practice in earlier years before joining Hogan and Hartson. He was general counsel of the Washington Loan and Trust Company until that firm merged with Riggs National Bank in 1954. He had been a director of Riggs Bank.

Mr. Bradley had served on the boards of the old Garfield Hospital, Columbia Hospital, the Louise Home and the Edes Home. He was a founding trustee of Washington Hospital Center.

He had been active with the former Washington Board of Trade and the Community Chest, a forerunner of the United Givers Fund.He had been a trustee of the Corcoran Gallery of Art and the Washington National Monument Society.

Mr. Bradley had served on the board of governors of the Metropolitan Club and Chevy Chase Club. He was a member of the Alibi Club and the Barristers. He had been active in the D.C. Bar Association.

Survivors include his wife of 52 years, the former Carolyn Chamberlain, of Washington; a son, Thomas, of Washington; a daughter, Carol Caswell of Lincoln, Mass.; a brother Fontaine C., of Washington; a sister, Mary Blagden of Waldoboro, Maine and eight grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the charity of one's choice.