Pesq. Vet. Bras. 32(8) Unique do ses of 7.5 and 10mg/kg induced characteristic clinical signs of Perreyia sp. larvae poisoning, increased GGT and AST values, and decreased glycemic curves. However, doses of 5, 10, and 15mg/kg repeated at 30 or 15 days intervals caused no disease and mild disease followed by death, respectively. These ϐin dings indicate that these animals probably developed some degree of tolerance to the toxins in P. ϔlavipes larvae. Ultrastru ctural examination of liver revealed proliferation of the smooth endoplasmic reticulum in the hepatocytes, which may be associated with an increased ability to metabolize toxins and could consequently lead to the tolerance observed in the present study. Further investigations may elucidate whether such tolerance effects could be applied as a control measure for P. ϔlavipes poioning or other hepatotoxic diseases. In addition, clinicopathological ϐindings were discussed. algum grau de tolerância para as toxinas presentes nas larvas de P. ϔlavipes. O exame ultraestrutural do ϐígado revelou proliferação do retículo endoplasmático liso de hepatóci-tos, o que pode ser associado a um aumento na capacidade de metabolizar toxinas e conseqüentemente levar à tolerância observada no presente estudo. Outras investigações poderão esclarecer se os efeitos de tal tolerância poderiam ser aplicados como medida de controle da intoxicação por P. ϔlavipes ou outras doenças hepatotóxicas. Além disso, os resultados clínico-patológicos foram discutidos.