To measure the incidence of sudden unexplained death in treated persons with epilepsy (SUDEP) and to identify risk factors for SUDEP, a cohort of 6,044 persons aged 15-49 years with more than four prescriptions for antiepileptic drugs (AEDs) was identified from the Saskatchewan Health prscription drug file. To exclude subjects whose sudden deaths (SUDs) might be misattributed to another chronic underlying disease, subjects with hospitalizations for cancer or heart problems were excluded. To exclude subjects without epilepsy, subjects with > 2-year AED treatment followed by AED-free time and subjects receiving