Studies in a Baltimore emergency room identified the patient with penetrating trauma as having the highest incidence of Human Immunodeficiency Virus Type I (HIV-1) infection. Anonymous testing over a 15-month period of 165 victims of penetrating trauma presenting to the Medical Center Hospital Emergency Center (San Antonio, Texas) revealed a 0% incidence of HIV-1. This data suggests that HIV-1 trauma patient incidence can be expected to vary between specific geographic areas and patient populations served, independent of community-wide AIDS incidence.