The effects of Russell’s viper venom on renal hemodynamics were studied in dogs. Intravenous injection of venom resulted in systemic hypotension, decreased renal blood flow and glomerular filtration rate. Venom injection in dogs pretreated with indomethacin caused less hypotension and less decrease in renal blood flow without changes in blood pressure and glomerular filtration rate. When the venom was injected directly into the renal artery, there was systemic hypotension, but urine flow was increased and renal blood flow and glomerular filtration rate were well maintained. Urinary N-acetyl-β-D-glucosaminidase was increased. Direct injection of the venom into the renal artery in indomethacin pretreated dogs decreased renal blood flow and glomerular filtration rate without change in systemic blood pressure. The findings indicate that the venom has a renal vasodilating effect which is prostaglandin mediated and also causes direct tubular injury. Renal blood flow is the net result of renal perfusion pressure, renal vasoconstriction and renal vasodilatation effec