Background. An increased load on components of the musculo-skeletal system caused by musical performance can lead to postural abnormalities and overstraining of the musculo-skeletal system in young performing artists. The aim of our research was to investigate the link over the long term between play on musical instruments by children, the type of musical performance, and disturbances of body posture. Material and methods. Our research involved a group of 113 primary music school pupils. The study was conducted in 1st, 2nd, and 3rd grade pupils, 7, 9 and 11 years of age respectively. The clinical examination consisted of a physical exam and an orthopedic evaluation of the musculo-skeletal system. A questionnaire indicating the type of instrument played and the body posture during play was also used. Results. The postural abnormalities found in this population included scoliotic posture, scoliosis, and thoracic muscle contraction. Many children showed several types of postural abnormalities coexisting. A statistically significant difference in the frequency of postural abnormalities was found, depending on how long the given musical instrument had been played after five years of attendance at the music school. Conclusions. Musical performance may increase the incidence and progression of some body posture disorders in music school pupils. The load imposed by the instrument being played leads to faster development of the clinical symptoms of scoliosis in girls than in boys. The appearance and progression of the body posture disorders may be contingent on how long the musical instrument is played. The progression of clinical symptoms in music school pupils depends on the type of music performance.