Sudden unexpected death in epilepsy (SUDEP) refers to sudden unexpected death in patients with epilepsy in whom autopsy fails to reveal an anatomic or toxicological cause of death. The purpose of this study was to examine associated factors and mechanisms relating to SUDEP in Victoria. The study was a retrospective study based on data from questionnaires completed by treating doctors and coronial files including police reports of death, autopsy and toxicology reports. The deaths were of people with epilepsy in Victoria that were referred to the coroner between 1991 and 1997. There were 15,751 coronial autopsies of which 357 had epilepsy and 50 (14%) were SUDEPs. The SUDEP rate was approximately 1 per 3000 epileptics per year. This study suggested the following associations: young age, tonic-clonic seizures, seizure frequency greater than 10/year, duration of epilepsy greater than 10 years, mental retardation, psychiatric disease and alcohol abuse. Antiepileptic drug (AED) compliance was rated by treating doctors as good in 24 cases. One or more postmortem AED drug levels was subtherapeutic in 30 of 50 cases. Only 5 were receiving psychotropic drugs; only 1 of these was receiving more than one of these drugs. A history of recent unusually stressful life event was present in only 4 cases. At least 11 showed evidence of terminal seizure, and the majority of events occurred in sleep. These observations support the hypothesis that seizures are the mechanism of many cases of SUDEP. The associations observed were largely in agreement with previous studies. However, seizure frequency was greater and duration of epilepsy greater than most previous studies. The role of factors such as AED compliance, psychotropic drug prescription and recent unusually stressful life event is less clear. This highlights the need for case-control studies of risk factors for SUDEP.