A series of 67 patients treated by Hartmann's operation was studied, special attention being given to complications originating from the rectal stump. In 13 patients, complications--abscesses of the rectal stump and fistulas from the rectal stump to the small intestine--were seen. Eight of those occurred in patients with leakage at the anastomotic site after anterior resection and in patients with radionecrosis of the rectum. It is concluded that the risk of rectal stump complications is slight in patients with diverticulitis and with carcinoma, who made up the large majority of those in whom Hartmann's operation may be needed.