BACKGROUND/AIMS: The aims of this study were to evaluate the change of gallbladder motility in gastrectomized patients and to investigate the change of gallbladder motility after administration of ursodeoxycholic acid (UDCA). METHODS: Prospective serial ultrasonographic study was performed in forty-six gastrectomized patients and thirty-seven healthy controls. Twenty-four patients who had low ejection fraction were studied after administration of ursodeoxycholic acid (1000 mg, daily). RESULTS: The mean fasting (FV) and postprandial (PV) gallbladder volume were significantly increased in gas trectomized patients (FV 30.2 +/-13.9 mL, PV 12.6 +/-6.4 mL), compared with controls (FV 17.2 +/-5.8 mL, PV 4.3 +/-3.3 mL). The ejection fraction of gallbladder in gastrectomized patients (56.9 +/-13.0%) was significantly lower than that in controls (75.5 +/-16.1%). The ejection fraction was recovered slowly after gastrectomy. However, there was no significant difference between UDCA-treated group (71.5 +/-11.9%) and non-treated group (71.4 +/-13.9%). CONCLUSIONS: Gastrectomy may increase the risk of gallbladder stones or sludges by inducing gallbladder dysmotility. Ursodeoxycholic acid does no seem to affect gallbladder motility.