The effects of basketball training on the maladaptive behaviors of 19 trainable mentally retarded children attending a special state school were investigated. Children in the experimental group took 7 weeks of basketball training (Special Olympics Inc.) designed for mentally retarded children, whereas the control group children engaged in free play activities with the ball. Both groups were assessed before the training and free play activity applications (preassessment), immediately after the applications (postassessment) and 30 days after the applications (follow-up assessment). All the children were observed (Classroom Behavior Checklist developed for this study) in their classroom during the academic tasks in which they were involved. Furthermore, their mothers were interviewed to get information about manifested maladaptive behaviors at home. To assess the children's level of improvement in basketball skills, the Sports Skills Assessment was utilized. Children trained in basketball skills showed a reduction in their level of maladaptive behavior both at home and in the school. This reduction was maintained in the follow-up period. Thus, basketball training can be proposed as an effective and practical rehabilitation program for trainable menially retarded children attending an institution. Copyright (C) 1997 Elsevier Science Ltd.