We studied behavioral factors that place intravenous drug users at risk for the acquisition and transmission of the human immunodeficiency virus (HIV) in a sample of 855 individuals not in drug treatment, living in central and southwestern Ohio. The HIV seropositivity rate for the sample was 1.5%. Three factors were significantly related to HIV infection: homeless shelter residence (odds ratio [OR] = 7.7, 95% confidence interval (CI) = 3.0-20.0), travel to northeastern HIV hyperendemic areas (OR = 5.2, 95% CI = 1.8-15.4), and recent male homosexual or bisexual behavior (OR = 11.2, 95% CI = 2.9-43.9).