to determinate the effect of the venom of young crotalus durissus cumanensis on levels of alt, ast and ap, balb/c mice were inoculated intraperitoneal with 0,75 mg/kg of purified venom. serum samples were obtained at different post-injection intervals (1, 3, 6, 12, 24h) and serum levels of alt, ast and ap were determined. a significative difference (p ？0,01) was observed in serum levels of alt at 6h and at 24h post-venom injection, with a maximum of 587,64 u/l at 24 h, when compared with controls. in addition, ast shows a significative elevation between 1h and 12h post venom injection, with a maximum level of 2327 u/l at 3 h, while ap only showed significant differences at 24 h post-venom injection. these results suggest that the venom of young crotalus durissus cumanensis induced liver-biliar injury, with a possible effect on skeletal muscle and/ or cardiac tissue.