Objective: To assess the functionality of the affected upper limb in children diagnosed with hemiplegia aged between 4 and 8 years after applying low-intensity modified constraint-induced movement therapy(mCIMT). Methods: Prospective case series study. A mCIMT protocol was applied for five weeks, with two hours of containment per day. The study variables were: quality of movement of the upper limb, spontaneous use, participation of the affected upper limb in activities of daily living, dynamic joint position, grasp-release action, grasp strength, supination and extension elbow movements. Four measurements were performed, using the QUEST scale, the SHUEE Evaluation, a hand dynamometer and a goniometer. Results: The sample was composed of 8 children with moderate manual ability. Statistically significant differences were detected in all the studied variables (p<0.05). The greatest increase occurred in spontaneous use from assessment 1-4 (p = 0.01), reaching 88.87% active participation in bimanual tasks. The quality of movement of the upper limb obtained a significant value due to the increase in dissociated movements and grasp (p = 0.01). Conclusion: A low dose (50 hours) of mCIMT increased the functionality of children diagnosed with congenital hemiplegia between 4 and 8 years of age with moderate manual ability.