Trauma centers and trauma registries have become important sources of data for trauma research. In their present form, both have serious biases in data selection, however, that can affect epidemiologic research results. This prospective study of 601 woodworking-related injuries seen at a trauma center involved a diverse population, a wide range of severities, both inpatients and outpatients, and primary versus referred patients. Eighty-eight per cent were outpatients and thus excluded by traditional trauma registries. Only 6% of primary patients, but 43% of referred patients, were hospitalized. Eighty-nine per cent of outpatients, and 28% of inpatients had AIS of 1. However, among primary patients 79% or more of lost or altered days of work, home, or recreational activity during 6 months postinjury occurred among ambulatory patients. Substantial differences were shown between hospitalized and ambulatory patients, and between primary and referred patients, in type of activity at time of injury, and in anatomic location and injury type. Trauma registry collection and analysis methods for epidemiologic research need substantial restructuring if they are to truly represent the tremendous problem of injury in our society.