-Sudden unexpected death in epilepsy (SUDEP) is the commonest cause of seizure-related mortality in people with refractory epilepsy. Several risk factors for SUDEP are described; however, the importance of including low temperatures as risk factor for SUDEP was never explored. Based on this, the aim of this study was to evaluate the heart rate of rats with epilepsy during low temperature exposure. Our results showed that low temperature clearly increased the heart rate of rats with epilepsy. Taken together, we concluded that exposure to low temperatures could be considered important risk factors from cardiovascular abnormalities and hence sudden cardiac death in epilepsy.KEy wOrDS: epilepsy, seizure, SUDEP, low temperatures, heart. É o frio responsável por mortes inesperadas em epilepsia ? Efeito de temperaturas baixas na frequência cardíaca de ratos com epilepsia.Resumo -A morte súbita e inesperada nas epilepsias (SUDEP) é considerada a maior causa de morte em indivíduos com epilepsia refratária. Vários fatores de risco para SUDEP têm sido descritos, no entanto, a inclusão das baixas temperaturas como um possível fator de risco para SUDEP não foi verificada até o momento. Nesse sentido, o objetivo desse estudo foi verificar a freqüência cardíaca de animais com epilepsia expostos as temperaturas baixas. Nossos resultados demonstraram que as baixas temperaturas são capazes de aumentar significativamente a freqüência cardíaca de animais com epilepsia. Dessa forma, concluímos que as baixas temperaturas podem ser consideradas um importante fator de risco de possíveis alterações cardiovasculares e até mesmo morte súbita cardíaca nas epilepsias.PAlAVrAS-chAVE: epilepsia, crises epilépticas, SUDEP, baixas temperaturas, coração. The epilepsies are the most common serious neurological condition. In developed countries, the incidence of epilepsy is around 50 per 100 000 people per year, and is higher in infants and elderly people 1,2 . The most commonly reported etiological factors are tumors, head injuries, stroke, genetic inheritance and infections of the central nervous system 1,3 . In resource-poor countries, endemic infections, such as neurocysticercosis and malaria seem to be major risk factors 1 . Moreover, people with epilepsy are two-to three-fold increase to die prematurely than those without epilepsy and the most common epilepsyrelated category of death is sudden unexpected death in epilepsy (SUDEP).SUDEP is defined as sudden, unexpected, witnessed or unwitnessed, nontraumatic and nondrowning deaths in patients with epilepsy, with or without evidence of a seizure and excluding documented status epilepticus (SE), in which post mortem examination does not reveal a toxicological or anatomical cause of death 4 . Information concerning risk factors for SUDEP is conflicting, but potential risk factors include: age, early onset of epilepsy, duration of epilepsy, uncontrolled seizures, seizure frequency, seizure type and antiepileptic drugs number 5 . The exact pathophysiological causes of SUDEP are unknown, b...