It has been shown that electropyrexia is an effective treatment for all forms of syphilis of the central nervous system. Temperatures at 41°C. (105.8°F.) and above, maintained for at least two hours, kill most of the treponemata pallida in the human body and, consequently, all chancres and skin lesions heal promptly after such treatment. The physiological changes observed during hyperpyrexia cannot account for the treponemacidal action of fever. The fever itself must, therefore, kill these organisms. All the treponemata are not destroyed by this therapy, since those that have reached the deeper tissues, especially the lymph glands, become heat and chemo-resistant. Therefore, it is advisable to combine pyretotherapy with arsenicals and heavy metals in the treatment of all forms of syphilis.