The importance of GABAergic neurons as the control sites at the central excitation level is generally accepted. Recently, knowledge has expanded concerning the participation of the GABAergic system in the pathophysiology of neurological and psychiatric diseases. Especially the pathogenesis of epilepsy is seen in connection with a loss of neuronal inhibitory function. Investigations into the structure and biochemistry of the central inhibitory transmitter GABA (gamma-aminobutyric acid) and the GABAA receptor resulted in medicinal-chemical strategies to stimulate GABAergic neurotransmission. With the synthesis of the GABA derivatives progabide, vigabatrin and gabapentin, a very promising enrichment of antiepileptic pharmacotherapy has become available.