Longitudinal study of forming of the posture was performed in 138 healthy pupils of Moscow school No. 710 aged from 6.5 to 14 of both sexes. Simultaneously children were examined anthropometrically and their constitution was determined after Schtefko. The posture was examined visually. It was established that posture forms within observation terms depending on sex, age and somatotype. Peak age for the risk of posture disturbance is 9-11 for girls and 10-12 for boys. Digestive and muscular somatotypes provide favourable prognosis respective to posture (in girls), while astenoid somatotype is the worst. Special type of posture defect is characteristic for each somatotype. In children with digestive and muscular somatotype primary posture defects disappear by 12-14. In children with astenoid and thoracal somatotype their number, in contrary, grows.