The study of neurotransmitter receptor localization at the microscopic level has been influenced by progress in biochemistry and molecular biology of these proteins and by the increasing development of new and more selective ligands. Receptor autoradiography is a well established technique in widespread use for the visualization and characterization of receptors at the light microscopic level. This technique can be readily used to examine receptors in control and diseased human brain tissues obtained post mortem. The applications of these techniques in human brain pharmacology and neuropathology as well as its limitations are discussed. The recent cloning of the genes coding for many neurotransmitter receptors has allowed the use of in situ hybridization histochemistry to demonstrate cells expressing mRNA coding for specific receptor subtypes. This technique is now being applied to human brain post mortem tissues. The results provided by the combination of these techniques will significantly modify our understanding of the chemical neuroanatomy of the human brain in health and disease.