Down syndrome is one of the commonest causes of developmental delay in children. Postural stability problems often exist with Down syndrome. To investigate the effect of core stability exercises on postural stability in children with down syndrome. Thirty children (21 boys and 9 girls) with down syndrome, with ages ranged from 6 to 10 years were participated in this study. They were assigned randomlyinto study and control group. Study group received core stability exercises and conventional physical therapy program while control group received Conventional physical therapy program. The duration of treatment was 8 weeks. Postural stability was evaluated pre and post treatment by Biodex *Balance System. There was a significant decrease in anteroposterior, mediolateral, and overall stability indices of the study group compared with control group post treatment (p < 0.001). Both groups showed a significant decrease in anteroposterior, mediolateral, and overall stability indices post treatment compared with pre treatment (p < 0.001). Eight weeks of core stability exercises is effective in improving postural stabilityand balance of children with Down syndrome. Core stability exercises should be considered as important part of the rehabilitation program for childrenwith Down syndrome.