Despite the availability of more than 20 different antiseizure drugs and the provision of appropriate medical therapy, 30% of people with epilepsy continue to have seizures. The approval of many new antiseizure drugs during the past two decades, including several with novel mechanisms of action, has not substantially reduced the proportion of patients with medically refractory disease. The safety and side-effect profile of antiseizure drugs has improved, but side effects related to the central nervous system are common and affect quality of life. Patients need new treatments that control seizures and have fewer side effects. This treatment gap has led patients and families to seek alternative treatments. Cannabis-based treatment for epilepsy has recently received prominent attention in the lay press and in social media, with reports of dramatic improvements in seizure control in children with severe epilepsy. In response, many states have legalized cannabis for the treatment of epilepsy (and other medical conditions) in children and adults.