The effect of nicardipine, a new dihydropyridine calcium antagonist, on postprandial colonic motility was assessed in 10 patients with irritable bowel syndrome. Each patient was studied twice receiving intravenously either N saline or nicardipine after a 1000 calorie meal. In the control study there was a significant (p less than 0.01) postprandial increase in the contractile activity of the colon, reaching a peak at approximately 20 minutes. Intravenous nicardipine completely abolished the colonic response, with a significant reduction in the number (p less than 0.005) and amplitude (p less than 0.005) of contractions and of the motility index (p less than 0.025). These results support the need for further studies to evaluate the therapeutic role of nicardipine in the irritable bowel syndrome.