&NA;Manometric studies of internal sphincter responses were carried out on 15 patients−14 with rectal prolapse and one with mucosal prolapse with proctitis cystica profunda. In all 12 patients studied preoperatively, the internal sphincter reflexes (inhibitory reflex) were absent or markedly obtunded. Anterior resection was performed on three of the patients in whom preoperative and postoperative manometric studies could be carried out. In one, the inhibitory reflex returned to normal after successful corrective surgery and in one, absence of the reflex persisted after anterior resection and this patient eventually had recurrent rectal prolapse.