The efficacy of the Crotalus durissus terrificus antivenom administration by intramuscular (im) injection at the same place of the im inoculation, of the C. d. terrificus venom was evaluated in mice. In three experiments two DL50 of the venom were inoculated and the antivenom was administered in three differents ways: half of the ED50 by intraperitoneal (ip) administration and half by injection, at the same place, immediatelly after the venom inoculation and thirty minutes after the im venom inoculation; four fifth of ED50 by ip administration and one fifth by injection, at the same place and thirty minutes after the venom inoculation. The antivenom that was administred by intraperitoneal route provided a higher protection to mice (a lower death rate in a 48 hours period) than when it was administred in parts, by intramuscular injection, at the same place of the venom inoculation (p<0,05). Therefore, it is concluded that this should not be used in human beings bitten by snakes.