Extracorporeal shock vave lithotripsy (ESWI.) with adjunctive oral ]itholytic therapy has proven to be a useful treatment in selected patients with gallbladder stones. To study the effect of ESWL on gillbladder dynamics, 99mTc-DISIDA hepatobiliary scintigraphy was done for 25 patients with symptomatic gallstones and 10 norrnal controls. Of these 25 patients, 15 were treated with ESWL and adjunctive oral litholytic agents (ESWL group) and 10 were treated only with oral litholytic agents (UDCA group). After overnight fast and gallbladder visualization on a routine hepatobiliary scintigra- phy with 7mCi of 99mTc-DISIDA, subjects were given fatty meal and imaged with a gamma camera interfaced to a computer (I frame/minute for i0minutes). A galibladder time-activity curve was generated and latent period (LP), ejection period (EP), ejection fraction (EF) ancl ejection rate (ER) v,ere calcutated, ESWL group were studied before, lday after and 2weeks after ESWL, and UDCA group were studied before and 2weeks after starting oral medication Mean basal EF was significantly reduced in patients but other parameters were not reduced. In ESlVL group, mean EF and mean ER at 1day after ESWL were reduced. In 3 of them, gallbladder was not visualized at all. Two weeks after ESWL, however, all parameters were recoverd to basal level. In UDCA group, all parameters were not changed significantly during medication. We can conclude that ESWL has such immediate adverse effect on gallbladder dynamics as reducing contractility ancl nonvisuaiization of gallbladder but it has no long-term effect.