Background: Idiopathic scoliosis is a three-dimensional deformity of the growing spine, affecting 2%-3% of adoles-cents. Curve detection before skeletal maturation gives a good opportunity for early treatment or prevention of curve pro-gression. Aim of Study: To investigate validity and reliability (intra-rater) of posture screen mobile (PSM) application in Adolescent idiopathic scoliosis (AIS). Material and Methods: Forty-one subjects (28 females & 13 males) with idiopathic scoliosis (30 thoracolumbar & 11 lumbar) participated in this study. Their mean ± SD for age, weight, height, and BMI were 17 (±1.2) years, 65.97 (±9.16) kg, 168.6 (± 6.4) cm and 23.1 (±2.04) kg/m2 respec-tively. Cobb's angles for each patient were predetermined by the radiologist before participating in this study. Each patient was clinically scanned by using two cameras (mobile phone & IPad) from four views (anterior, posterior, right lateral, left lateral). Following digitization, the application calculates the translations and angulations of different spinal segments. Results: Moderate positive significant correlation for T1- T4 (r=0.4, p=0.009), and strong positive significant correlation for T4-T8, T8-T12, T12-L3 and L3-PSIS (r=0.82 to 0.89), p=0.0001) were found between Cobb's angle and spinal segment angulation measured by posture screen mobile. On the other hand moderate positive significant correlation for T1-T4 (r=0.6, p=0.009), and strong positive significant cor-relation for T4-T8, T8-T12, T12-L3 and L3-PSIS (r=0.8-0.9), p=0.0001) were found between Cobb's angle and segment translation that measured by posture screen mobile.Intra-rater reliability of the Posture screen mobile suggested excellent agreement for spinal segment angulation (ICC: 0.99) and spinal segments translation (ICC: 0.92-0.97). Conclusion: PSM application is valid and reliable in screening posture deviations for patients with idiopathic scoliosis. It is an easy, quick, safe, affordable, user-friendly, low-cost screening method, and noninvasive for clients and patients.