Since the literature concerning the chemistry and toxic effects of tetryl has been reviewed by other writers, we have intentionally avoided repetition and confined our remarks to the clinical experiences and observations of the medical department of an arsenal with the hope that we shall be of practical assistance to physicians who have patients working in the munitions industry. Our study of the effects of tetryl was made on a working population of about 800 to 900 employees in the tetryl areas. Although most of the workers were engaged in loading operations, some were doing research work and manufacturing tetryl. To make our study complete we included a very small group that worked in the areas but had no direct contact with tetryl, such as guards, janitors and clerks. These employees were observed in the work rooms, in the dispensary and during periodic examinations, which in most cases were done