Epilepsy affects almost 1% of the population, and yet the pathophysiology of this disorder is unknown in the majority of the cases. Recently, a number of mutations in different genes were identified, mostly in cases of familial epilepsy with a Mendelian mode of inheritance. The majority of these genes code for voltage- or ligand-gated ion channels. Interestingly, not only generalized epilepsies, but also focal epilepsies were shown to be caused by mutated genes, which in some cases are expressed ubiquitously in the brain. This review will focus on the monogenic familial epilepsies and the clinical and molecular aspects of these diseases.