Complications related to the retained rectal remnant were reviewed in 136 patients undergoing subtotal colectomy for acute ulcerative colitis. Fifty-five patients (Group 1) had a closed rectal stump brought up into the subcutaneous tissue, and 30 (Group 2) had an open mucous fistula. These were compared with an intrapelvic Hartmann's pouch performed in 51 patients (Group 3). All patients eventually had a pelvic pouch procedure. Age, duration and activity of disease, and preoperative steroid use were similar in all groups. There was no mortality. The rectal stump in 19 Group 1 patients (35 percent) spontaneously opened, and seven (13 percent) developed local left lower quadrant wound infections. Two Group 1 patients (4 percent) developed pelvic septic complications, as compared with two Group 2 patients (7 percent) and six Group 3 patients (12 percent). Subsequent pelvic dissection was difficult in 20 percent of Group 3 patients, vs. 4 percent and 0 percent of Group 1 and Group 2 patients, respectively (P less than 0.05). Persistent rectal disease activity was present in 41 percent of Group 3, vs. 27 percent of Groups 1 and 2. Our study suggests that exteriorization of the closed rectal stump following subtotal colectomy is associated with fewer pelvic septic complications and minimal local morbidity, facilitates subsequent pelvic dissection, and is not associated with increased disease activity in the retained rectum.