Mary Frances Mitchell Tiffey, 78, a former nurse and lifelong area resident who was active in service and social organizations, died of cancer Saturday at her home in Silver Spring.

Mrs. Tiffey was born in Washington and lived in Chevy Chase before moving to Silver Spring. She was a graduate of old Tech High School. She graduated from the Army School of Nursing at the Walter Reed Medical Center in 1925 and was a visiting nurse for the next four years.

Her professional memberships included the Visiting Nurses, the Kiwanis Wives, Columbia Country Club, and the Sherwood Forest Club, a social organization. She was a member of the Shrine of the Blessed Sacrament Catholic Church, and was active in St. Gertrude's Guild, a fund-raising organization for a school for retarded girls.

Survivors include her husband of 52 years, Robert P. Tiffey, a builder and former savings and loan director, of Silver Spring; a son, Edward L., of Rockville; two daughters, Mary Covell, also of Rockville, and Anne Pobiak of Potomac; a brother, Lee Mitchell of Winter Park, Fla.; a sister, Ruth Fitzpatrick of Silver Spring, and 16 grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to St. Gertrude's School for Retarded Girls, or Children's Hospital.