gamma-Aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the central nervous system. GABA receptors have been classified into at least two categories, GABA(A) receptors, which are heterogeneous multimeric ligand-gated Cl channels, and GABA(B) receptors, which are coupled to G-proteins. GABA(B) receptors have not only a physiological role in synaptic transmission, but also are important in pathological conditions associated with absence epilepsy, cognitive disorders and nociception. This review describes our current knowledge of the neuropharmacology and neurochemistry of GABA(B) receptors, including their heterogeneity as well as the therapeutic potential of the drugs which interact with these sites.