The D3 dopamine receptor is a member of the D2-like family of G protein-coupled receptors. It was cloned and characterized almost 25 years ago. A key feature of the D3 dopamine receptor system, which has attracted considerable attention, is its anatomical localization remarkably restricted to the limbic circuitry. This has spurred the hypothesis that D3 involvement could contribute to the pathophysiology of neuropsychiatric disorders (or to some features of neuropsychiatric disorders), including but not limited to psychosis, addictions and substance abuse, mood and movement disorders.