[Purpose] This study examined possible interrelationships between postural sway and posture parameters in children and adolescents with a particular focus on posture weakness. [Subjects and Methods] 308 healthy children and adolescents (124 girls, 184 boys, aged 12.3 ± 2.5 years) participated in the study. Posture parameters (posture index, head protrusion, trunk inclination) were determined based on posture photos in the sagittal plane. Postural sway was measured during 20 seconds on a force plate. The Pearson's product-moment correlation coefficients between the anthropometric and posture parameters and the sway path length (SPL) were calculated, as well as the coefficient of determination R2. [Results] There is a weak but significant correlation between age or body mass index of the test subjects and the SPL. There is no statistically significant correlation between posture parameters and the SPL. Children and adolescents with posture weakness do not exhibit a changed SPL. [Conclusion] Therefore, therapy of poor posture must be considered separately from therapeutic measures for the improvement of balance skills.