The jararacucu, one of the most dreaded snakes of ing amputation in one) and five local abscesses. Two Brazil, southern Bolivia, Paraguay and northeastern became shocked and four developed renal failure. Argentina, is a heavily-built pit viper which may Three patients, aged 3, 11 and 65 years, died 18.75, grow to a length of 2.2 m. Up to 1000 mg (dry 27.75 and 83 h after being bitten, with respiratory weight) of highly-lethal venom may be milked from and circulatory failure despite large doses of specific its venom glands on a single occasion. It has antivenom and intensive-care-unit management. In accounted for 0.8% to 10% of series of snake bites two patients, autopsies revealed acute renal tubular in Sa˜o Paulo State, Brazil. We examined 29 cases necrosis, cerebral oedema, haemorrhagic rhabdo- of proven jararacuc¸u bites recruited over a 20-year myolysis at the site of the bite and disseminated period in two Sa˜o Paulo hospitals. Severe signs of intravascular coagulation. In one survivor with local and systemic envenoming, (local necrosis, chronic renal failure, renal biopsy showed bilateral shock, spontaneous systemic bleeding, renal failure) cortical necrosis; the patient remains dependent on were seen only in patients bitten by snakes longer haemodialysis. Effects of polyspecific Bothrops anti- than 50 cm; bites by shorter specimens were more venom were not impressive, and it has been sug- likely to cause incoagulable blood. Fourteen patients gested that anti-Bothrops and anti-Crotalus developed coagulopathy, six local necrosis (requir- antivenoms should be given in combination.