27 patients with Hirschsprung's disease and 49 patients with idiopathic megacolon were followed for a period ranging between 6 months and 15 years. The diagnosis is essentially based on the barium enema and functional ano-rectal investigations. Duhamel's operation was performed in 26 patients with Hirschsprung's disease and in 34 patients with idiopathic megacolon. There was no mortality, but 10 cases of pelvic suppuration required colostomy, 9 of which were temporary. 8 cases of anastomotic stenosis developed as a late complication, but they were easily dilated by a simple surgical procedure. One patient developed sexual dysfunction (retrograde ejaculation). A good result was obtained in all patients with Hirschsprung's disease, except for one case of adynamic colon. Two patients with idiopathic megacolon were lost to follow-up. All but two of the remaining patients obtained a good or excellent result. Other operations were performed for idiopathic megacolon: 6 sphincterotomies, with 3 successes and 3 failures; 15 sigmoidectomies, including 3 with sub-peritoneal anastomosis (State's operation). There were 5 good results, 6 mediocre results and 4 failures which subsequently required a Duhamel's operation. Other techniques were performed more rarely: Swenson's operation with a short-term technical failure, 3 side-to-side ileo-sigmoid anastomoses with 3 failures which required a sub-total colectomy with ileo-sigmoid anastomosis. The longterm result was mediocre. The trans-rectal, colo-anal descent of the colon therefore appears to be the treatment of choice in megacolon in adults of whatever cause.