A task force of the Department of Health, Education, and Welfare conducted a survey aimed at estimating the incidence of research- related injuries, with a view to determining the feasibility of compensating subjects injured during research. The data were obtained by telephone from 331 investigators conducting research on nearly 13,000 human subjects over the past three years. Eighty-five investigators reported at least one injury. Of the 4957 reported injuries, 3926 were classified as trivial, and 974 as temporarily disabling; of 57 injuries resulting in death or permanent disability, one disabling stroke, not clearly related to the research, occurred three days after a nontherapeutic procedure; the rest resulted from treatments expected to benefit the patients directly, usually cancer chemotherapy. The data suggest that the risks of participation in nontherapeutic research may be no greater than those of everyday life, and in therapeutic research, no greater than those of treatment in other settings.