The regional distribution of D3 dopamine receptors was studied in human brain by quantitative autoradiography with [3H]7-hydroxy-N,N-di-n-propyl-2-aminotetralin ([3H]7-OH-DPAT). The highest densities were found in the ventral striatum/nucleus accumbens, followed by the remainder of the neostriatum, cerebral cortex, and cerebellar cortex. Moderate amounts were found in the substantia nigra. Low densities of D3 dopamine receptors were visualized in pituitary gland (posterior lobe > anterior lobe), amygdala, and hippocampus. The globus pallidus and thalamus contained lower densities. The distribution pattern is much more widespread as detected by in situ hybridisation histochemistry for D3 mRNA in human and in rat brain. Our data confirm a predilection of D3 receptors in brain areas involved in cognitive and emotional functions. The presence of D3 receptors in non-limbic parts of the neostriatum and substantia nigra suggests that they also play a role in the dopaminergic control of motor processes. Its precise function in cerebellum and pituitary gland is at present uncertain.