Sudden unexpected death in epilepsy (SUDEP) is the most important direct epilepsy-related cause of death. Patients with refractory epilepsy are at especially high risk of SUDEP. SUDEP occurs predominantly at night and unwitnessed, and can best be regarded as a fatal tonic-clonic seizure. While its pathophysiology is incompletely understood, SUDEP is most probably triggered by a number of predisposing and precipitating factors, including seizure-induced respiratory depression and cardiac arrhythmia. Achieving seizure freedom is the best way to prevent SUDEP. Nocturnal supervision may be another alternative preventive strategy, but this requires further research.