Purpose: This study was done to develop and test the effectiveness in late school-aged children of a healthy lifestyle education program for cancer prevention. Methods: Participants were 26 students in the sixth grade of N elementary school in J City (experimental group) and 25 students in the sixth grade of D elementary school with same educational conditions (control group). The research design was a nonequivalent control group pretest-posttest design. Data collection and execution of the study were carried out from March 10 to May 19, 2011. For the experimental treatment, 7 weekly sessions of the healthy lifestyle education program for cancer prevention were given by the researcher. Posttest was done immediately following the conclusion of the program and 4 weeks later. Frequencies, percentages, ${chi}^2$-test, t-test, repeated measures ANOVA and paired t-test with SPSS WIN 18.0 were used to analyze the data. Results: Perceived barriers, perceived self-efficacy, activity related effect and family support significantly influenced cancer prevention knowledge and increases in healthy life styles. Conclusion: Results indicate that, as this program for cancer prevention was effective in increasing healthy lifestyle practices in these children, there is a need to further develop, test and implement programs in all schools.