Introduction. Body build and the ability to maintain balance play an important role in the development and improvement of specialised motor habits and complex technical elements necessary to achieve significant sporting results in rhythmic gymnastics. The aim of this study was to determine changes in the level of ability to maintain dynamic balance and in the construction of somatic young female rhythmic gymnasts during a period of two year training. Material and methods. The research material consisted of 13 girls. When the first measurements were taken gymnasts were aged 7 - 12 years. In the study we utilised posturography and the Heath-Carter Anthropometric Somatotype Method. The analysis of the study showed that there were statistically significant differences (p <0.05) in the values of the dynamic balance indicators of the gymnasts' bodies in all three consecutive measurements over a course of years. Results and conclusions. It was noted that as the young gymnasts progressed in their training, their ability to maintain dynamic balanced increased. Based on the characteristics of the model, we developed an exemplary set of dynamic balance of rhythmic gymnasts. The somatotype of the tested athletes surveyed had been changing in the direction of increase in the proportion of components of endomorphy and mesomorphy. The balance ability of rhythmic gymnasts stabilised during their puberty associated with changes in body proportions ratio i.e.: height, weight and somatotype. The results and conclusions drawn can be an important part of selection and choice and can be used to control the dynamic balance in rhythmic gymnastics.