Purpose: To assess changes observed in knowledge, attitudes toward people living with human immunodeficiency virus (HIV), self-efficacy and behavioral intentions of senior secondary school students after an HIV/AIDS (acquired immune deficiency syndrome) educational intervention in Vinnitsa, Ukraine. Methods: A quasi-experimental, nonequivalent control group design with pretest-posttest components was employed. Two secondary schools (intervention and control) were randomly assigned to the study. A random sample of the 15-16-year-old students (100 participants in each school) completed anonymous self-reported pre- and postintervention questionnaires. In addition, a three-month follow-up questionnaire was administrated in both schools to assess the longevity of the intervention outcomes. Outcome scale scores were compared between the two groups on baseline, first, and second posttests separately. We used the Pearson chi-square test for categorical data and a t-test for difference in mean scores. Results: After intervention we observed significantly higher knowledge, attitudes, and self-efficacy scores among students in the intervention school than in the control school (96.2 ± 6.2 [SD] vs. 82.6 ± 8.3, respectively, p < .01; 24.4 ± 4.4 vs. 21.7 ± 4.8, respectively, p < .01; 21.9 ± 2.6 vs. 20 ± 3.8, respectively, p < .01). As a result of the intervention, we also report significantly higher proportions of students in the intervention school than in the control school who would not intend to use alcohol and narcotics and who intend to use condoms (p < .01). Conclusions: Our AIDS education program was able to considerably improve students' knowledge, attitudes and self-efficacy, and promoted positive changes in participants' behavior intentions; it should therefore be extended to more schools to multiply its effects. However, in the context of evaluation, studies with actual HIV-risk behavior outcomes are urgent for Ukraine. © 2006 Society for Adolescent Medicine.