To assess whether gallbladder motility is altered in patients with irritable bowel syndrome (IBS) or essential dyspepsia (ED), we studied gallbladder function in 25 healthy volunteers, 20 patients with IBS, and 22 with ED. By real time ultrasonography, we studied the following parameters: (a) fasting gallbladder volume, (b) maximum percent of gallbladder emptied, (c) time required for maximal contraction, (d) residual volume after maximal contraction, and (e) percent fasting volume at 2 h. All parameters, except fasting gallbladder volume, were measured after a high-fat meal. The fasting gallbladder volume, maximum percent of gallbladder emptied, time required for maximal contraction, residual volume after maximal contraction, and percent fasting volume at 2 h in controls and patients with IBS was 19.3 +/- 8.8 ml and 24.4 +/- 9.7 ml, 67.1 +/- 10.7% and 67.6 +/- 13.5%, 41 +/- 20.6 min and 49.7 +/- 25.3 min, 6.2 +/- 3.3 ml and 7.6 +/- 5.3 ml, and 38.1 +/- 12.2% and 40.7 +/- 14.5%, respectively. The differences between the two groups were statistically not significant. The corresponding values in patients with ED were 15.5 +/- 6.3 ml, 57.6 +/- 16.5%, 51.8 +/- 29.3 min, 6.1 +/- 3.2 ml, 44.1 +/- 17%, respectively. Compared with controls there was no statistically significant difference in these parameters, except the maximum percent of gallbladder emptied, which was significantly less than that in controls (57.6 +/- 16.5% vs. 67.1 +/- 10.7%; p less than 0.05). Therefore, we could not find that patients with IBS have any abnormality of gallbladder function; postprandially, patients with ED have submaximal contraction of the gallbladder.