Anorectal myectomy has been shown to provide clinical benefit to patients with outlet obstruction. Long-term results of anorectal myectomy have been evaluated in 57 patients operated on between February 1984 and February 1988 with a median follow-up of 24 months. Overall improvement was recorded in only 31 percent of patients. Spontaneous evacuation without the need for laxatives was recorded in only 11 patients (19 percent), while 38 (67 percent) had no functional improvement. Results were independent of preoperative colonic transit or histologic evidence of aganglionosis. Anorectal myectomy identified aganglionosis in 23 percent of patients with chronic constipation, but there was minimal long-term benefit from the procedure.