Sulpiride, a benzamide derivative, selectively antagonizes dopaminergic receptors within and outside the central nervous system. Dopamine has previously been shown to increase colonic motility. In the present investigation the motor response of the pelvic colon to a standard 1000 calorie meal was studied in 12 patients with the irritable bowel syndrome. The meal induced a significant increase in motor activity, lasting for 1 h and greatest in the first 30 min. In 6 cases the administration of sulpiride 100 mg i.m. significantly reduced the postprandial increase in colonic motor activity. Thus dopaminergic receptors may be involved in the colonic motor response to food.