Spine deformations and faulty posture may be evaluated by assessing trunk surface deformation. POTSI index (Posterior Trunk Symmetry Index) was introduced in 2003 to assess asymmetry of the trunk seen from the back. However, deformations may also affect the anterior surface of the trunk and this can be noticed more easily by the patient owing to the visual accessibility of the anterior surface. This study a new parameter called ATSI (Anterior Trunk Symmetry Index) in order to assess the anterior trunk deformation. study was conducted on fifty primary school children, boys and girls aged 6-7 years. One photograph of each child in a spontaneous standing position was taken with a digital camera. The photographs were analysed to obtain a quantitative assessment of the new parameter, ATSI, by means of computer software developed in collaboration with an IT specialist. The intra-observer error found in the analysis was 1.23. The interobserver error was 3.08. The average ATSI value for 50 children was 25.3 ± 10.6. The threshold value norm defined as mean+2SD was 46.5.