Neda Rabeei - Student Research Committee, Mashhad Branch, Islamic Azad University, Mashhad, Iran
Aghile Heydari - Student Research Committee, Mashhad Branch, Islamic Azad University, Mashhad, Iran
Zeinab Sadat Hosseini - Student Research Committee, Mashhad Branch, Islamic Azad University, Mashhad, Iran

Epilepsy is the sudden and abnormal discharge of the nervous tissue of the brain. It is a debilitating and chronic condition and it is the mostcommon disease of the nervous system which it’s prevalence is 0.5-1% in people. Despite Existing treatments 30% of patients still suffer from epileptic seizures. Cannabinoids seem to have neuroprotective and anti-epileptic effects. Our goal is to systematically reviewthe effect of cannabinoids in the treatment of epilepsy. Systematic search of Embase, PubMed, Science Direct and Google Scholar databases was done between 2013- 2018 with the terms of Cannabis OR Cannabinoids AND Epilepsy . We included epidemiological andexperimental studies about the medical effects of cannabinoids on the treatment of epilepsy including quasi-experimental, RCTs, non-RCTs, cohort studies, analytical cross-sectional studies and case-control studies. Data extraction was done using a standardized data extraction tool in Microsoft Office Excel 2013. All the analyses were done using Stata V.15.0. . 28 studies were identified including 19 observational studies, and 9 randomized controlled trials (RCTs). The mean age of participants was 18.7 years. Using Cannabinoids 18 mg/kg per day had more effective role in reducing the seizure than placebo (frequency by 50%+RR 1.53, 95% CI 1.15 to 2.580). The number of Cannabinoids neededfor treatment of one person to experience 50%+ reducing the seizure was 6 (95% CI 4 to 12). By investigating the 12 observational studies, 53.2% (95% CI 29.01% to 64.05%) of patients reported 50%+ reducing the seizure. In 7 observational studies 7.7% (95% CI 4.8% to 19.0%)were seizure-free. Conclusion: According to the studies were reviewed, RCT investigations are rare in pediatric samples and severe epilepsy syndromes; RCT studies other syndromes and cannabinoids are required.