The mortality rate is increased in patients with epilepsy, and especially among patients with drug-resistant epilepsy. This increased mortality is mainly related to the risk of SUDEP whose incidence is between 3.5 and 9 per 1,000 for patients with drug-resistant epilepsy. The term SUDEP refers to a sudden death occurring in a patient with epilepsy in whom anamnestic and post-mortem evidence does not identify a particular cause. Experimental and clinical data strongly suggest that most of SUDEP result from a postictal respiratory dysfunction progressing to terminal apnea. Due to the major role of serotonin in regulating breathing rhythms and data in animal models of epilepsy, it is envisaged that an alteration of serotonergic systems of the brainstem and limbic regions may play a central role in the occurrence of SUDEP. The objective of this work is to look for abnormalities of the serotonergic transmission within regulatory regions of respiratory and autonomic functions in brain samples prospectively collected in patients died from SUDEP.