This work search relations between functional impairments imputed to hypothalamus and organic lesions in Chagas' disease. The author used rats with T. cruzi inoculation by intraperitonial way. Histopathologic and quantitative neuronal studies were done by serial sections of hypothalamus. It was demonstrated that the anterior hypothalamic region is more parasited than others, with greater neuronal destruction also. The author suggests that impairments of glycidic and thyroidian metabolism, of sweating and potassium blood level, must be considered as sequels of these lesions.