Robert George Brewster, 54, who retired last December as a member of the Senior Intelligence Service of the Central Intelligence Agency, died of cancer Tuesday at his home in Great Falls, Va.

During his 27-year career with the CIA, Mr. Brewster served in posts in East Asia for 15 years. He also was a branch chief at CIA headquarters and supervisor of a large training program for senior officers.

When he retired, he received the CIA's Distinguished Intelligence Medal and the Secretary of Defense's Meritorious Civilian Service Medal. He also received certificates of merit from the CIA and foreign governments.

Mr. Brewster served in the Army Air Forces in Europe during World War II.

He was a native of Chicago and a 1948 graduate of Loyola University there. In 1952, he earned a law degree from Kent College of Law in Chicago.

Survivors include his wife of 30 years, the former Virginia Murphy of Great Falls; four sons, Robert G., of Edmundton, Canada; Thomas P., of Spokane, Wash.; Brian, of Alexandria, and Kevin, of Great Falls; three daughters, Patricia Geoghegan of Boca Raton, Fla., Katherine Rose, of Burke, Va., and Terese, of Great Falls; a brother, William, of New Jersey, and two grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to Hospice of Northern Virginia, Inc. in Arlington.