We present a first, proof­of­concept experiment of the MAWii music therapy system, which uses Wiimotes as virtual instruments. This experiment involves four groups of children suffering from behavioral disorders and currently treated in a day hospital in Paris. Preliminary analysis shows that the system is robust, that patients were strongly motivated by it and that their behaviors and verbal expressions had rich psychodynamic content. Future work will entail further experimentation to explore new venues for game technology in music therapy, to assess the therapeutic value of our approach and to automatically extract pertinent data from therapy session recordings