Metabotropic glutamate receptor mGluR3 is a G protein-coupled receptor for glutamate. Glutamate is the major excitatory neurotransmitter in the mammalian central nervous system and functions to regulate excitability via pre- and postsynaptic mechanisms. The mGluR3 receptor is widely expressed in glial cells but also shows discrete localization both pre- and postsynaptic on glutamatergic and other neurotransmitter synapses. It is also expressed within forebrain regions including hippocampus and thalamus. Agonists of mGluR3 have been shown to suppress enhanced glutamatergic excitations in brain synapses known to be involved in the expression of fear/anxiety in animals and humans. It is anticipated that mGluR3 receptor represent a promising new target for treatment of anxiety and stress-related disorders in humans.