A study was made on the presence or absence and the degree of histopathological renal cell damage, in hypotensive anesthesia models with prostaglandin E1 (PGE1) or trimethaphan. Cell damage was most noticeable in the S3 segment, the straight and second half part of the proximal renal tubule. The lesion was evaluated and semiquantified. The trimethaphan group in this area exhibited degeneration--including cell vacuolation and granule increase in this site, as well as cytoclasis such as cell fragments in the lumen, luminal extension, flattening of epithelial cell and damage of distal renal tubular columns. In the PGE1 group, cell degeneration was milder than in the trimethaphan group, and there were no cytoclasis findings. Renal cell damage in the PGE1 group was slighter than in the trimethaphan group.