Abstract 1. 1. We have presented an instance of actinomycosis of the sigmoid colon treated by resection of the sigmoid colon. 2. 2. Penicillin, achromycin and potassium iodide proved effective in the postoperative management of this disease which was complicated by infection with Escherchia coli in the abdominal wall. No sinus developed from the site of the anterior resection. 3. 3. Repeated follow-up by means of barium enema for nearly five years showed no evidence of recurrent infection.