To aid in determining health care service needs, Wisconsin Department of Health and Social Services DHSS data on Wisconsin hospital discharges for traumatic brain injury TBI, using ICD-9-CM codes for intracranial injury with and without skull fracture, and Wisconsin Department of Transportation data on incapacitating non-fatal head injuries INHI from traffic accidents from 1989 through 1992 were reviewed. Yearly TBI hospital discharges in Wisconsin declined 15.0%, and by 23.9% for Milwaukee County residents, over 1989 through 1992, correlating closely with changes in yearly INHI in Wisconsin (r= 0.999;p<0.01) and in Milwaukee County (r= 0.989;p<0.05). Using 1990 census data the yearly TBI risk ratio for Milwaukee County residents compared to the rest of Wisconsin increased from 1989 (1.76) to 1990 (1.92) and then decreased in 1991 (1.83) and 1992 (1.51). The results of this pilot study suggest there was a decrease in the incidence of hospitalization of patients with TBI in Wisconsin from 1989 through 1992, paralleling a decline in INHI from motor vehicle accidents. There appeared to be a relatively greater decline in these patients in Milwaukee County from 1991 to 1992 as compared to the rest of the state. The techniques employed in this study may be used to help assess rehabilitation service needs in other areas.