Tolerance indices were determined, allowing for the effects of body mass, for thirteen mammalian species using the results of experiments in which animals were exposed near a normally reflecting surface to shocked blast waves whose durations ranged from 0.24 to 400 msec. A general equation was developed for expressing the interrelations between overpressure, duration of the blast wave, body mass, and probability of survival. The species were divided into high- and low-tolerance groups applicable to "large" and "small" mammals, respectively. Since the available evidence indicated that man is more likely to be a member of the high-tolerance group, the tolerance index arbitrarily, but tentatively, assigned to him was the geometric mean of those for the large species. Using criteria developed in experimental studies, the results of the overall analysis were made applicable to free-stream situations in which the long axis of the body is perpendicular or parallel to the direction of propagation of a shocked blast wave.