The aim of the research is to investigate whether physiotherapy exercises can decrease asymmetry of passive mechanical properties of skeletal pair muscles. In this research, 17 schoolchildren from 8 to 16 years of age participated. In the first group, 7 children had cerebral palsy. In the second group, there were 10 children without physical and movement impairments. The subjects were treated with 10 sessions of physiotherapy on the therapeutic ball. Passive mechanical properties of the muscles were measence between children with and without CP was observed. The research showed that exercises of physiotherapy on the therapeutic ball imitating horseman’s movements decreased asymmetry of stiffness and tone of gluteus medius muscles of children with and without CP and only partially decreased asymmetry of stiffness and tone of their lumbar erector spinae.