We investigated the effects of group music intervention on aggression and self-esteem in children with highly aggressive behavior. Forty-eight children were allocated to either a music intervention group or an untreated control group. The music intervention group received 50 min of music intervention twice weekly for 15 consecutive weeks. The outcome measures were Child Behavior Checklist Aggression Problems Scale (Parents), Child Aggression Assessment Inventory (Teachers) and Rosenberg Self-esteem Scale. After 15 weeks, the music intervention group showed significant reduction of aggression and improvement of self-esteem compared with the control group. All outcome measures were significantly lower in the music intervention group than prior to treatment, while there was no change in the control group. These findings suggest that music can reduce aggressive behavior and improve self-esteem in children with highly aggressive behavior. Music intervention is an easily accessible therapy for children and as such may be an effective intervention for aggressive behavior. Further more, objective and replicable measures are required from a randomized controlled trial with a larger sample size and active comparable control.