. Constipation is one of the most common gastrointestinal symptoms in children with neurological disorders. This study was performed to compare the therapeutic effect of polyethylene glycol (PEG) plus domperidone with PEG plus placebo in the treatment of chronic constipation in children with cerebral palsy. . In this a double-blind clinical trial study was done on the children with cerebral palsy who had chronic constipation and was referred to Mohammad Kermanshahi hospital of Kermanshah city in the west of Iran. The participants were randomly divided into 2 groups with 2 therapies of PEG combined with domperidone (case group, n = 21) and PEG with placebo (control group, n = 21). The information was extracted from patients based on the checklist before and after treatment and the response to treatment in the 2 groups were determined and compared. The data were analyzed by T-test or Mann-Whitney U test to compare quantitative variables and Chi-square and Fisher's exact tests for comparing qualitative variables. . In both case and control groups, all Rome IV criteria for a diagnosis of chronic constipation except incontinence were significantly reduced after treatment. However, the successful response rate in the case group (PEG + domperidone) was 90.5%, while this rate was 61.9% in the control group. . Based on the results of the present study, it seems that PEG plus domperidone had a positive effect on the treatment of children with cerebral palsy and chronic constipation.