Abstract Review evidence for cannabinoids as adjunctive treatments for treatment-resistant epilepsy. Systematic search of Medline, Embase and PsycINFO was conducted in October 2017. Outcomes were: 50%+ seizure reduction, complete seizure freedom; improved quality of life (QoL). Tolerability/safety were assessed by study withdrawals, adverse events (AEs) and serious adverse events (SAEs). Analyses were conducted in Stata V.15.0. 36 studies were identified: 6 randomised controlled trials (RCTs), 30 observational studies. Mean age of participants was 16.1 years (range 0.5–55 years). Cannabidiol (CBD) 20 mg/kg/day was more effective than placebo at reducing seizure frequency by 50%+(relative risk (RR) 1.74, 95% CI 1.24 to 2.43, 2 RCTs, 291 patients, low Grades...