This report clarified the direct damage to renal cell ultrastructure on shock wave exposure. The renal cortex of the rabbit was exposed to the shock waves (1200 bar) generated by the piezo-ceramics. The change was examined by electron microscopy immediately after 20 shots exposure and 500 shots exposure as well as one week after 500 shots exposure. In all groups, the most critical damage was observed in the proximal tubule. Immediately after 20 shots exposure, large vacuoles were found to be enclosed by infoldings in the proximal tubular cell. The damaged cell lost its brush border and jutted out into the lumen. The ruins of organelles (nuclei, mitochondria, etc.) were seen in the lumina of proximal and distal tubules. The damage progressed, in the 500 shots exposure group, to include the distal tubular cytoplasm. One week after the 500 shots exposure, a few of atrophic tubular cells were found in wide scars. The tubular cell which contained a deformed nucleus and destroyed organelles was desquamated from the basement membrane. The change in the tubular cell after shock wave exposure was apparently different from that after such intervention as one hour ischemia. It was concluded that the direct damage to renal cells by underwater shock wave exposure was really present.