In a retrospective review of 311 patients having subtotal colectomy for ulcerative colitis, information on the fate of the rectal stump was obtained in 288. Proctectomy was performed in 159 patients (55 percent); for persistent proctitis in 118 (41 percent), cancer prophylaxis in 37 (13 percent), and cancer in four (1.4 percent). One hundred twenty-two patients (42 percent) had ileorectal anastomoses. Eighty-four of these (69 percent) retained a functioning ileorectal anastomosis at the time of follow-up or death, one to 22 years later, and an additional six patients (5 percent) had a satisfactory ileorectal anastomosis for five to 14 years before proctectomy. Cancer developed in the rectal stump in nine patients (3.1 percent), underscoring the need for either proctectomy (total or mucosal) or long-term surveillance of the retained rectum. However, subtotal colectomy, by permitting ileorectal anastomosis or other sphincter-preserving surgery at a later date, does have a definite place in many patients requiring surgery for ulcerative colitis.