Marjorie Anderson De Witt, 79, a resident of Alexandria since 1951, when her husband, Brig. Gen. Calvin De Witt Jr., retired from the Army, died Friday at De Witt Army Hospital at Fort Belvoir following a stroke.

Mrs. De Witt was born into an Army family at Chattanooga, Tenn. She was educated at Lausanne, Switzerland, and graduated from the Benett School in Millbrook, N.Y.

She was married in 1925 and accompanied her husband to various Army posts in the United States. She also accompanied him to France for a tour of duty there in 1930 and 1931 and to Germany during the occupation there after World War II.

The hospital at which she died was named after Brig. Gen. Wallace De Witt, an officer in the Army Medical Corps who died in 1947. Wallace De Witt was a brother of Mrs. De Witt's husband.

Mrs. De Witt was a member of the Army & Navy Club in Washington.

In addition to her husband, of the home in Alexandria, survivors include two sons, Army Col. Calvin De Witt III, of Fort Monmouth, N.J., and William De Witt, of Williamstown, Mass; a daughter, Mrs. William Robertson, of Alexandria, and four grandchildren.