Gabapentin ( Neurontin) is currently utilised in the treatment of a range of neurological and psychiatric conditions, including partial epilepsy, neuropathic pain and bipolar disorders. Gabapentin (GBP) mechanisms of action, although extensively investigated, are only partially known. This review examines GBP-mediated effects on voltage- and ligand-gated neuronal ionic currents. GBP binds in vivo to the alpha-2-delta sub-unit of the calcium channel and, in dorsal root ganglia, GBP-induced modulation of calcium conductance plays a central role in the drugs inhibitory effect on pain transmission. Less clear is the relevance of GBP as a calcium current modulator in central neo-cortical neurons and the potential use of GBP as add-on therapy for resistant seizures. GBP is also reported to interact with NMDA receptor currents, inwardly rectifying potassium channels and a subtype of baclofen-sensitive-receptors. The potential utility of GBP in modifying the balance among released endogenous amino-acids, and also in neuroprotection, has been suggested. It is, however, unclear whether - and through which cellular pathways - GBP might give therapeutic benefit in the course of neurodegenerative disorders.