Moiré pictures of fifty-five normal children and 195 cases of scoliosis patients were analyzed. Among them 40 cases were treated surgically by 3-D Harrington instrumentation. Cobb angle, and the coronal plane asymmetry indices (FAI, HDI), POTSI and Hump Sum were analyzed. A slight trunk asymmetry were detected in the normal children. The mean values of all the parameters in the scoliosis group were significantly larger than those in the normal cases (p< 0.01). A weak correlation was found between POTSI and Cobb angle (r=0.435, p< 0.0001). The preoperative POTSI of 46.9 decreased to 24.3 postoperatively. Lateral curvature and trunk deformity including hump and trunk asymmetry should be evaluated separately because these are three different major factors of scoliois. Therefore, Cobb angle, Hump Sum and POTSI must be measured in the evaluation of scoliosis treatment. The new parameter introduced here as POTSI is clinically useful to assess the trunk deformity quantitatively.