1. Ninety-eight adult female rats were injected with 14 micrograms/g B. jararaca venom intraperitoneally to determine functional and histopathological renal changes. 2. Glomerular filtration rate, renal plasma flow, filtration fraction, osmolar clearance, water transportation in collecting ducts, urinary sodium excretion, fractional sodium excretion, albuminuria, urinalysis, plasma creatinine, urinary output and mean arterial pressure were studied before and 24 and 48 h after venom administration. Light microscope examination of the kidneys was carried out in another group of rats before and 2, 5 and 24 h after venom administration. 3. Treated animals developed acute renal failure characterized by a decrease in glomerular filtration rate, osmolar clearance, and fractional and urinary sodium excretion, and by an increase in plasma creatinine. There was also a decrease in renal plasma flow and mean arterial pressure. Histopathological examination of the kidneys indicated mild proliferation of the mesangial matrix and degenerative changes of the tubules characterized by loss of brush border and cytoplasmic vacuolation. 4. The hemodynamic changes probably played an important role in the pathogenesis of the functional and histopathologic renal changes developed by the animals after venom injection.