Five patients who developed acute renal failure due to acute tubular necrosis following multiple hornet (Vespa orientalis) stings are described. All of them had intravascular hemolysis. Evidence for rhabdomyolysis was present in 2 patients. Two patients had elevated transaminase and alkaline phosphatase levels and in 1 of these, liver biopsy showed centrilobular necrosis. Two patients had thrombocytopenia in the absence of disseminated intravascular coagulation. Two patients died of infections while the remaining 3 recovered completely. Acute renal failure following multiple hornet stings appears to result mainly from intravascular hemolysis or rhabdomyolysis although a direct nephrotoxic effect of venom cannot be excluded.