Background and purpose : Drug abuse is one of the most serious problems among the Korean adolescents today and has been associated with delinquent behavior in adolescents. The number of adolescents who abuse drugs is increasing yearly. Solutions to the problem, however, have not been well developed. The purpose of this study was to determine the effectiveness of a drug use prevention program which was developed by researchers. The program was a modified DARE(Drug Abuse Resistance Education) program for Korean adolescents. Methods: This study used an experimental, one-group pretest-posttest design with a convenience sample of 122 middle school students who were at one middle school located in Seoul. Data were collected using a self-administered questionnaire where ‘knowledge and attitude about drug use’, ‘social skill’, and ‘self-esteem’ were measured. The program had 12 sessions to improve knowledge and attitudes towards drugs, decision making skills, social resistance skills, management of stress and self-esteem of students. Teaching strategies for each session were varied lectures, group discussion. role-playing, question-and-answer sessions and audiovisual materials. Paired t-test was used to analyze the differences between the pre- and post-test scores on knowledge of and attitudes towards drug use, social skills, and self-esteem. Results : There were significant differences in knowledge and attitudes about drug use between pretest and post-test (p＜.05), but no significant differences in social skill and self-esteem(p＞.05). Conclusion: Our results showed that the drug use prevention program was not effective in promoting social-skill and self-esteem of Korean adolescents. These findings might be due to the respondents being in the period of early adolescence (puberty) and not being good at group discussion. So, further study is needed to develop a drug use prevention program appropriate to students 9 and 10 years old, and to encourge small group discussion.