Study subjects included 88 male and female high school students in a small midwestern city. Data were collected during the fall of 1987 for students who received a short educational unit on AIDS earlier in the school year. Study materials consisted of a page of general directions; a 9-item demographic section requesting information about the student's sex, class year, marital status, religion, political preference, and ethnic origin; the Andre and Moses Sexual Responsibility Scale; and an experimenter-designed AIDS knowledge test. Results showed that most adolescents were familiar with basic facts about AIDS. Performance was better on knowledge items dealing with HIV transmission and risk groups than on items dealing with basic medical facts about AIDS. Over 90 percent knew that vaginal or anal intercourse without a condom and sharing intravenous needles put them at risk and that having sex with multiple partners increased the risk of HIV infection. A substantial number of students, however, lacked some basic information, and students occasionally expressed contradictions about AIDS transmission. Students higher in sexual responsibility had greater knowledge of AIDS. Implications of the study findings for educational programs designed to communicate AIDS information to high school students are discussed. 31 references and 2 tables