Background: Changes in the lifestyle of school student are one of the most important factors for the postural problems that are developing in students. This study aims to find the reliabity of postural measurements within trial and across trial measurements. Method: In this study, 97 middle grade school students (10- 11 years) were included. Photographs were taken in sagittal plane in 2 trial and 3 sessions which were assessed quantitatively and reliability was calculated. Results: Postural measurements of upright position in both within trial and across trial were found to be significant reliable. Conclusion: The study reveals significant intra subject reliability of upright postural measurements.