Abnormalities of the autonomic nervous system function and cholecystokinin release have been described in patients with irritable bowel syndrome. Because the autonomic nervous system and cholecystokinin have an important role in the normal functioning of the gallbladder, we studied gallbladder contraction in response to a meal, using real time ultrasonography in irritable bowel syndrome patients (n = 20) and healthy controls (n = 15). The following parameters were studied: 1) fasting gallbladder volume, 2) residual volume after maximal contraction and at the end of 2 h, 3) maximum percent of gallbladder emptied, and 4) the time taken for maximal contraction. Fasting gallbladder volume (26.21 +/- 1.81 ml vs 15.21 +/- 1.63 ml, p < 0.001), and residual volume after maximal contraction (14.2 +/- 1.69 ml vs. 5.86 +/- 0.98 ml, p < 0.001) and at the end of 2 h (18.81 +/- 1.73 ml vs. 11.65 +/- 1.45 ml, p < 0.01) were significantly higher in the patient group, compared with controls. The maximum emptying was less (49.55 +/- 2.75% vs. 63.98 +/- 4.55%, p < 0.01) and the time taken for maximal contraction (59.25 +/- 3.8 min vs. 42.33 +/- 2.04 min, p < 0.001) was longer in the patient group than in the controls. Based on these observations, we conclude that patients with irritable bowel syndrome have significant abnormalities of gallbladder motor function.