This study was designed to test the effects of human potential seminar on mental health and self-concept of juvenile delinquents. The subjects were consisted of 21 boys and 10 girls attending three Mental Health Programs which were provided as the rehabilitation programs for juvenile delinquents referred from a probation office. Watching video tapes about drugs, having personal unfoldment and peak experience, sharing personal past experiences of maladaptive behaviors each other, acknowledging personal strengths, utilizing art therapy to overcome personal anger, remembering ones who she/he loved, planning her/his behavioral modification, making a time capsule, and having candle ceremony are the strategies which were applied to the subjects in the human potential seminar. The intervention program was administered by a researcher and two assistants who were trained for counselling. Total 40 hours group therapy was carried out within 5 days. After finishing group therapy, the investigators had follow-up meeting with the subjects regularly once per month for seven months The subjects participated in main programs and subsequent follow-up meeings from November, 1997 to May 1999. Mental health was measured with SCL-90-R and self-concept were measured with Self-concept Scale developed by Fitts. The data were analyzed by percent, repeated measures ANOVA, and Bonferroni multiple regression using SAS program. The results were as follows: 1. The level of obsessive-compulsive, depression, anxiety, hostility, paranoid ideation, psychocitism decreased significantly after treatment at 0.05 level. 2. Self Satisfaction which was one of the subscales of the subscales of Self-Concept increased significantly at seventh month after treatment. However there were no significant differences between pre-test score and post-test score of the remaining subscales of Self-Concept such as Total Positive Self, Self-Identity, Self Behavior, Physical Self, Moral Ethical Self, Personal Self, Family Self, Social Self. These results indicate that human potential seminar which was provided with group therapy was effective in improving mental health for juvenile delinquents, but it is not effective in enhancing all those sub-dementions of self except self satisfaction. That is, the human potential seminar may be more effective in promoting mental health than in enhancing self-concept of juvenile delinquents.