Purpose: This study was done to examine the effects of a smoking prevention program on primary school students. Method: The design for this study was a nonequivalent quasi-experimental control group pretest-posttest. The smoking prevention program was provided to grade 5 and 6 students selected from two schools in Jecheon. The experimental group consisted of 72 students and the control group, 73 students. A smoking prevention program composed of smoking prevention education (once a week for 40 minutes over a period of 8 weeks) and supportive environment for smoking prevention was developed by modifying several smoking prevention programs. The research was conducted from May 15 to October 10, 2003. Result: 1) After completion of the smoking prevention program, the mean scores for knowledge about smoking, attitude to smoking, and intention toward non-smoking were not significantly different between the experimental group and the control group. Conclusions: To affectively achieve the aims of a smoking prevention program, the effectiveness of the program should not be measured over the short term only. Long-term tracking of students educated in the program, to identify the rate of those who later become smokers needs to be done.