Background: Hemiplegic cerebral palsy (CP) occurs as a result of injury to the sensorimotor cortex that controls one side of the body. It affects one side of the body, including the limbs, trunk, and potentially the neck. The ability of hemiplegic children to reach, hold, and manipulate objects with their hands is one of their biggest challenges. Purpose: The study aimed to identify how cross-education affected the activity and function of the affected upper limb in children with spastic hemiplegic cerebral palsy. Additionally, it aimed to determine the effect of contralateral isokinetic resistance training on strength in children with spastic hemiplegic cerebral palsy. Methodology: Thirty two spastic hemiplegic cerebral palsied children aged from 5 to 7 years participated in this study. They were assigned randomly into two equal groups: Control group (A) received a designed physical therapy program for 60 min / three sessions per week and study group (B) received the same designed physical therapy program given to control group (A) in addition to isokinetic resistance training for the shoulder abductors of the contralateral upper limb in concentric mode at the angular velocity of 180 degree/ second. The concentric isokinetic shoulder abductors peak torque in Newton- meters and average power were assessed by isokinetic dynamometer apparatus. The ability of the child to perform the reaching skills was assessed by the Modified Functional Scale for Reaching. All variables were assessed before and after two successive months of intervention. Results: The results revealed significant improvement in the shoulder abductor torque, power average and reaching in both groups with favor of study group (B). Conclusion: Adding contralateral isokinetic training to the designed physical therapy program is effective for improvement of strength and reaching skill in children with spastic hemiplegic cerebral palsy.