Illán de Vacas belongs to the "comarca" of Torrijos. It is bordered on the north by the municipality of Los Cerralbos, on the northwest by Otero, on the east by Domingo Pérez, on the south by Cebolla and on the west by Lucillos.
The town lies at an elevation of roughly 480 m, and is located 59 km west of Toledo and 35 km east of Talavera de la Reina, on the rail line between Talavera and Torrijos. It is approximately 95 km southwest of Madrid.
The municipality contains a church dedicated to the Assumption of Our Lady.