The aim of this study was to evaluate the effects of gymnastics training combined with music on balance, loco-motor level and coordination in children with autism spectrum disorder (ASD) and down syndrome (DS). This randomized, controlled experimental trial included 30 children (15 children with DS, 15 children with ASD) aged 8 to 14 years. The children were separated into 2 groups, as Group 1 in which ASD and Group 2 in which DS treated gymnastics training with music for 16 weeks, 2 days a week, 1.5-2 hours. Flamingo balance test, functional reach test, Wall Catch coordination test and flexibility test were used to evaluate balance, dynamic balance, loco-motor level and coordination, flexibility, respectively. All groups were evaluated before training and at the end of 16 weeks. When the pre-training and post-training parameters were compared between the groups, a increase was determined in the parameters of balance, loco-motor level and coordination, flexibility in Group 1. This increase was statistically greater in Group 1. Statistically significant difference was determined in Group 2 with respect to functional reach test, sit and reach test values. No statistically significant difference was determined in Group 2 in respect of Flamingo and Wall Catch coordination tests. As a result; gymnastics training combined with music were found to be effective in increase balance score, improving loco-motor level, coordination, flexibility in children with DS and ASD. The results of this study can be considered to provide important contributions to the understanding and treatment of children with autism and down syndrome.