Body posture is determined by many factors, including central regulation connected with anti-gravitational mechanism which develops in ontogenesis. Postural disorders arise as a result of a compensatory anti-gravitational mechanism, in which the main component is reduced postural tone (volume and distribution disorders). Compensation mechanisms consist in improper alignment of particular body segments (distribution disorders) (e.g., increase or decrease of spinal curvatures, external or internal rotation of the lower limbs, valgus and varus deformity of the knees and feet). Such disorders may constitute a reason for abnormal component development, thus limiting trunk rotational mobility.An aim of the study was to assess the range of trunk rotational mobility.Pupils (n=123) aged 13-15 underwent the following parameter evaluations: 1. Posture according to Kasperczyk's scoring method, 2. Postural tone volume by analysis of pelvis control in the long sitting, 3. Range of trunk rotation with use of upper tension test (muscle latissimus dorsi and thoracolumbar fascia).Positive tension test was recorded in 32 children (21 unilateral and 11 bilateral). Diversification of statistical averages of scoring for body posture, from the lowest (x=6.41) in 91 subjects with negative tension test, to the highest (x=7.72) in 11 subjects with double-sided positive result was recorded. Statistical analyzes confirmed significance of correlation between body posture's quality and trunk's rotational mobility (r=0.286 at p=0.001), as well as between volume of postural tone and range of trunk's rotational mobility. Coefficients of correlation amount to, respectively, for tension test and free sitting position r=0.187, p=0.038; and for tension test and corrected sitting position r=0.253, p=0.05. Disorders of muscle tone volume and distribution cause limitation of trunk rotational mobility development.