The diagnosis of epilepsy is often incorrect, potentially in up to 20% of cases, so should be revisited if seizures are not responding to treatment. SIGN recommends that the diagnosis of epilepsy should be made by an epilepsy specialist, ideally in the setting of a dedicated first seizure or epilepsy clinic. Diagnosis relies primarily on the history. Distinguishing between a genetic generalised epilepsy and a focal epilepsy is vital as this influences investigation, treatment and prognosis.