Retired Army Gen. Melvin Zais, 64, who commanded a paratroop battalion in World War II, the 101st Airborne Division and the XXIV Corps in Vietnam, and the 3rd Army in the United States, died of cancer Tuesday at his home in Beaufort, S.C.

At the time of his retirement from the Army in 1976, Gen. Zais commanded Allied Land Forces in Southeastern Europe with headquarters at Izmir, Turkey. Before taking that post in 1973, he commanded the 3rd Army at Fort McPherson, Ga.

A native of Fall River, Mass., Gen. Zais graduated from the University of New Hampshire and was commissioned through the Reserve Officers Training Corps. During World War II, he commanded a battalion of the 517th Parachute Infantry Regiment and led it in a night parachute assault in southern France. He subsequently served as the regiment's executive officer.

His assignments between the end of World War II and his Vietnam service included various posts in this country and abroad. He first went to Vietnam in 1966. In 1968, he returned there and commanded the 101st Airborne and then the XXIV Corps. He was assigned to the Joint Chiefs of Staff in Washington before commanding the 3rd Army.

Gen. Zais' decorations include five Distinguished Service Medals, two Silver Star medals, four Legions of Merit and two Distinguished Flying Crosses.

His first wife, Margorie Aileen Emert Zais, died in 1967.

Survivors include his wife, the former Patricia Vachon Light, whom he married in 1967, of Beaufort; two sons, Army Lt. Col. Barrie E. Zais and Army Maj. Mitchell M. Zais, both of whom are stationed at the Military Academy at West Point, N.Y.; two stepsons, David R. Light of Columbus, Ohio, and John P. Light of Beaufort; two brothers, David of Tiverton, R.I., and Lawrence, of Hollywood, Fla., and one sister, Ruth Gollub, also of Hollywood, Fla.

The family suggests that expressions of sympathy be in the form of contributions to the Vietnam Veterans' Memorial Fund, 1025 Connecticut Ave. NW, Washington, 20036.