Primary variables of aerospace are altitude, radiation, motion, thermal extremes, and weightlessness. With respect to drug studies, only the first four have been explored directly. Secondary variables include the general nonspecific stress of the aerospace situation and operational performance considerations. These have been studied with respect to pharmacologic questions. Finally, another variety of compounds has been tested under one or more aerospace variables. Therapeutic and prophylactic usefulness for conditions unrelated to environmental stress have made this broad group of drugs available for inclusion in this review.