OBJECTIVE Gallbladder emptying is reduced in many patients with cholesterol gallstones. To clarify the role of impaired gallbladder motility in recurrent gallstone disease, the effect of gallbladder emptying on the formation of recurrent stones was studied prospectively. METHODS In 54 consecutive patients with single radiolucent gallbladder stones, postprandial gallbladder emptying was assessed sonographically before lithotripsy and 1.8 +/- 0.1 years (mean +/- SE) after gallstone disappearance. Patients were followed up for gallstone recurrence for 0.6-4.1 years (median, 2.6 years). RESULTS After gallstone disappearance, gallbladder fasting volume (33.7 +/- 3.4 vs. 27.8 +/- 3.0 mL; P = 0.007) and residual volume (12.6 +/- 1.9 vs. 9.7 +/- 1.3 mL; P = 0.010) decreased, whereas the ejection fraction remained unchanged. However, gallbladder volume did not differ whether initial or recurrent stones were present. Gallbladder emptying was more impaired in patients with than patients without later recurrence (47% +/- 5% vs. 63% +/- 2%; P = 0.001). Cox analysis showed that gallbladder emptying was an independent determinant of the risk of gallstone recurrence (P = 0.002). Within 3 years, recurrent stones formed in 53% (actuarial analysis) of patients with an ejection fraction of < 60% but in only 13% of patients with an ejection fraction of > or = 60%. CONCLUSIONS Gallbladder emptying is an important factor in the formation of recurrent gallstones.