OBJECTIVES: Most children and adolescents have low levels of cancer knowledge and awareness, and infrequently engage in preventive behaviors. This study examined the effects of a short classroom-based intervention for cancer prevention on knowledge, attitude toward cancer preventability, self-efficacy, and behavioral intentions of fifth-grade elementary school students. METHODS: The study was based on a pre-post-follow-up, 2-group, quasi-experimental design. Participants in the intervention group attended two 40-minute sessions on cancer prevention education and watched a music video about cancer prevention, while participants in the control group were only exposed to the music video. Self-reported knowledge, attitude toward cancer preventability, self-efficacy, and behavioral intentions were assessed 1 week pre-intervention and post-intervention, as well as 3 months post-intervention. RESULTS: The 3-month post-intervention results revealed partial effects, indicating that the education intervention improved knowledge and attitudes toward cancer preventability; however, no effects were observed on self-efficacy and behavioral intentions 3 months after the intervention. CONCLUSIONS: Long-term regular booster sessions are required to improve not only social-cognitive factors, but also behavioral intentions, which could result in behavior changes promoting cancer prevention.