Between October 1985 and June 1989, most active duty US Army soldiers were screened for human immunodeficiency virus (HIV) antibody. Of 648,032 screened soldiers in this analysis, 1,588 were HIV-antibody positive. In a multivariate analysis, correlates of positivity included: age [Adjusted Odds Ratios (ref less than 20 years) = 20-24 years, 3.7; 25-29, 9.3; 30-34, 15.7; greater than or equal to 35, 15.9]; being male, [4.2]; being Black or Hispanic (vs white) [3.7 and 3.0, respectively]; being single (vs married) [3.8]; assignment to an HIV endemic location [1.7], and having a medical occupation [2.7, 2.7, and 2.6 for negligible, low, and high blood exposure professions, respectively]. Seropositivity rate ratios for medical vs non-medical personnel were 0.7 [95% CI = 0.4, 1.4] for females and 2.9 [95% CI = 2.5, 3.3] for males. For male medical personnel, being single (vs married) correlated strongly with antibody positivity [prevalence ratio = 3.4, 95% CI = 2.6, 4.6]. Excess HIV risk among medical personnel appeared largely attributable to factors other than occupational exposures.