Weakness of the sound side in hemiparetic cerebral palsy is one of the serious complications which affect these children. Many children with hemiparetic cerebral palsy have diminished muscle power in the neglected sound side, and the application of strengthening exercises aim to improve the muscle strength and function activities and so may be helpful in the management of such cases. In this study, endurance exercises and treadmill training was conducted to investigate its effect on increasing the strength of the quadriceps femoris and hamstring muscles of the sound side in spastic diaplegic cerebral palsy in comparison to the effect of an endurance exercise program. Thirty spastic hemiparetic children were the sample of this work. There were divided randomly into two equal groups. The ratio of peak torque of quadriceps femoris muscle and the hamstring muscle and balance were measured before and after six months of the application of the treatment program. Group A received the physiotherapy program and treadmill training, while group B received endurance exercise in the form of DeLorme resistance exercise in addition to the same physiotherapy program given to group A. Significant improvement were observed in all measuring variables when comparing the post-treatment results in both groups. Conclusion Walking training may be considered as one of the most helpful methods in management of muscle weakness in the sound side and balance in spastic hemiparetic cerebral palsied children.