PURPOSE: In order to evaluate microstructural changes after shock wave exposure, gross, light microscopic and transmission electron microscopic findings were analyzed with rabbit gallgladders. MATERIALS AND METHODS: A preliminary study(2 rabbits) was performed to determine the dosage intensity of shock waves needed to inflict damage, using a EDAP LT 01 piezoelectric extracorporeal shock wave Iothotriptor. The gallbladders of three different groups of rabbits were given shock waves of various intensity. A storage value of 100, 50, 25 at rate of 20/sec under 80% power were given to group I (4 rabbits), group II( 4 rabbits), and group III(3 tabits), respectively. The rabbits were sacrified 6--12 hours later. RESULTS: The observed pathologic changes in the transmission electron microscopy were vaculization of cytoplasm and swelling of epithelial cells with dilatation and structural alteration of intracellular organelles, especially endoplasmic reticulum. Cell membrane rupture and necrosis were observed at the markedly affected area. The structural changes of intracellular organelles were minimally found at a storage value of 25. However, above pathologeic changes with dilatation and structural alterations of endoplasmic reticulums were more profund at value of 100. CONCLUSION: Early histologic changes induced by shock waves are dose dependent and the findings of cellular damage caused by ESWL might be explained as above.