Trace amines are endogenous molecules structurally related to classical biogenic amines that are linked to psychiatric conditions. A family of G-protein coupled receptors referred to as trace-amine-associated receptors (TAAR) are activated by trace amines and are present in very low levels in mammalian tissue. TaRs contain several structural features that are similar to the rhodopsin ∫-adrenergic receptor superfamily, including the positions of the seven transmembrane regions that provide common ligand-binding pockets as well as the short N- and C-terminal domains. TAAR proteins are potential targets for drugs of abuse, such as amphetamine and MDMA, as well as neuropsychiatric disorders including schizophrenia, depression, and attention deficit disorder.