Lake Junin Giant Frog Batrachophrynus macrostomus Peters, 1873, native and endemic from Andean high plateau ecoregion, is a Peruvian wildlife specie vulnerable to extinction. The water quality is a main factor of importance for captivity breeding of the Lake Junin Giant Frog. The effects of three metals Hg2+, Cd2+ and Pb2+ in laboratory conditions were evaluated on 26 and 27 larval stage of B. macrostomus tadpole proceeding from zoo breeding place La Huaycha, Junin. The values of mean lethal concentration (LC50 in mg L-1) for ecotoxicological static bioassays between 24 and 96 h of exposure oscillated between 15 to 390 μg L-1 for Hg2+, between < 125 to 760 μg L -1 for Cd2+ and also among < 10 to 30 μg L -1 for Pb2+. The sequence in general showed a decreased order of ecotoxicity: Pb2+ > Hg2+ > Cd 2+. The results show that this species are highly sensible to the action of these three heavy metals. The acute toxicity of these three heavy metals was compared with other water species. Finally, a research of environmental risk assessment was performed to analyze the possibility of reintroduction of this species to its natural environment, Lake of Junin.