The authors surveyed a sample of 132 medical students to assess their behaviors related to the risk of HIV infection. Scale measures were computed for survey questions relating to both occupational and nonoccupational behavior and also for questions relating to knowledge of any worry about HIV infection. Regression analysis to assess the influence of demographic characteristics, knowledge, and worry on occupational and nonoccupational behavior indicated that (1) medical students are more likely to implement behaviors to protect themselves from occupational exposure to HIV infection than from nonoccupational exposure and (2) students who worried more about HIV infection reported less at-risk occupational behavior. Implications of these findings for intervention efforts with medical students are addressed.