III Corps () was a corps of the Army of the Republic of Vietnam (ARVN), the army of the nation state of South Vietnam that existed from 1955 to 1975. It was one of four corps in the ARVN, and oversaw the region of the country surrounding the capital Saigon. The Fifth Division based in Bien Hoa on the northern outskirts of Saigon was a part of III Corps, and due to the division's close proximity to the capital was a key factor in the success or failure of the various coup attempts in the nation's history.