The purpose of this study was to determine whether extracorporeal shock wave lithotripsy(ESWL) of gallstones alters contractability and volume of the gallbladder in response to a fatty meal. The gallbladder was examined by ultrasonography before and after ESWL. Eight patients with gallstones and seven healthy volunteers were included in the study. Gallbladder contractbility was not altered in all of the patient after ESWL, although gallbladder confraction was already delayed and less complete in gallstone patients, compared with healthy controls(residual volume; 33.8%$pm$18.3% VS 10.0% $pm$ 3.7%, half contraction time; 37.8$pm$21.7min VS 23.1$pm$6.9min). These findings suggest that ESWL has no immediate adverse effects on gallbladder motility. The residural volume and half contraction time in gall stone patients were 33.8%$pm$18.3% and 37.8%$pm$21.7min. In the healthy control group the two values were 10.0%$pm$3.7% and 23.1$pm$6.9min.