Epilepsy is one of the most common primary brain disorders. In many patients the cause of epilepsy is still enigmatic. In recent years limbic encephalitis (LE) has been diagnosed in a significantly increased number of patients. Whereas paraneoplastic LE is since many years a well-known disease, affecting patients with a peripheral tumor, nonparaneoplastic LE represents a recently identified syndrome, which preferentially affects healthy adults. Clinically, patients with nonparaneoplastic LE present frequently with sudden onset of temporal lobe epilepsy accompanied by a serious impairment of their episodic memory. The syndrome is characterized by antibodies against neuronal antigens. However, little is known about the etiopathogenesis of this syndrome. Our main focus is to analyze a putative role of neurotrophic viral infections in the context of nonparaneoplastic LE and other focal epilepsy syndromes as well as the identification of novel autoantibodies and their neuronal targets.