Purpose: The purpose of this study was to determine the effect of neuromuscular electrical stimulation of abdominal and back muscles simultaneously on gross motor function measures (GMFM) in children with unilateral cerebral palsy. Materials and Procedures: Thirty children with unilateral spastic cerebral palsy participated in this study. They were classified randomly into two groups of equal numbers, control, and study groups. GMFM was used to evaluate function in the two groups before and after ten successive weeks of application of the treatment programs. The control group (A) received a selected physical therapy program based on the neuro-developmental approach used for rehabilitation of such patients and the control group received the same selected physical therapy program applied to the study group in addition to 30 minutes of neuromuscular electrical stimulation of abdominal and back muscles simultaneously. Results: Comparing the pre-and post-treatment results for the control and study groups revealed significant improvement in GMFM. Post-treatment significant improvement was recorded in favor of the study group. Conclusion: There was an effect of neuromuscular electrical stimulation of abdominal and back muscles simultaneously on function in children with unilateral cerebral palsy.