Perineal hernia is an uncommon complication following abdominoperineal resection. The aim of the study was to evaluate the predisposing factors and the optimum method of repair. A retrospective review of patients with postoperative perineal hernia at the Massachusetts General Hospital between 1963 and 1995 was performed. Twenty-one patients with perineal hernias were found. The original perineal operations were as follows: abdominoperineal resection in 13 patients, pelvic exenteration in 5 patients, cystourethrectomy in 2 patients, and perineal resection of the rectal stump in 1 patient. The incidence of symptomatic perineal hernia following abdominoperineal resection was estimated to be 0.62 percent. A total of 69 percent of patients had the original perineal wound left partially open, and in 10 percent it was left completely open. The peritoneal defect was not closed in 53 percent of patients, and only 21 percent had closure of the levator defect. Of the 19 patients who had hernia repair, 13 were repaired transperineally and 3 transabdominally and 3 required a combined abdominoperineal approach. The repair methods were as follows: simple closure of the pelvic defect (10 patients), mesh closure (5 patients), gluteus flap (1 patient), and retroflexion of the uterus (2 patients) or bladder (1 patient). Four patients had postoperative complications (mostly wound infections), and the recurrence rate was 16 percent. There was no difference in length of hospitalization among transperineal, transabdominal, and combined approaches. Primary closure of the perineal wound, with careful avoidance of wound infection is the most important consideration for avoiding a perineal hernia. Repair via the perineum with simple closure of the defect or a mesh is successful in most cases.