Some U.S. states now allow the use of cannabis for medical treatment. Many patients with epilepsy have wanted to try cannabis as a treatment even though preclinical and clinical evidence is limited. As mentioned above, several clinical studies have investigated CBD after the late 19th century. Recent studies have shown an effect of CBD in treating epilepsy (Table 1). They suggest that CBD can reduce the frequency of seizures, reducing monthly frequency in most types of seizures. Many studies have included a significant number of patients with Dravet syndrome (DS) and Lennox-Gastaut syndrome (LGS), and have observed reduced seizures as an effect of CBD.