Several of the established α1-, α2- and β-adrenoceptors have now been isolated and cloned. The in situ hybridization method has been used to map the distribution of many of these adrenoceptors within cells of the CNS. These studies add complementary and new information to our knowledge of adrenoceptor localization provided previously by radioligand-mediated autoradiography. Neuronal cell groups containing one or more mRNAs for seven adrenoceptor subtypes throughout the rat CNS have been mapped. In the present review Anthony Nicholas, Tomas Hokfelt and Vincent Pieribone will examine these localizations and discuss the additional information these maps supply, as well as some implications for understanding central noradrenaline and adrenaline systems.