Abstract Objective We report our findings regarding effectiveness, safety, and tolerability of cannabidiol (CBD)-enriched medical cannabis as add-on therapy in children with drug-resistant epileptic encephalopathies (DEEs) after a median follow-up of 20 months. Methods A prospective cohort study was conducted to assess effectiveness, safety, and tolerability of CBD-enriched medical cannabis oil added to standard antiseizure medications in children with drug-resistant DEE seen at a single center. Results Between October 2018 and March 2020, 59 patients were enrolled. Mean age at enrollment was 10.5 years (range, 2–17 years). Median treatment duration was 20 months (range, 12–32). Median age at first seizure was 8 months (range,...