In vitro quantitative autoradiography was used to visualize nicotinic receptors in large cryosections of human brain hemispheres. Sections 80 microns thick of human brain hemispheres were incubated with (-)-[3H]nicotine and the distribution of nicotinic receptors in human brain was studied. Increasing numbers of nicotinic binding sites were observed in the: hippocampus less than cortex less than cerebellum less than substantia nigra less than putamen less than periaqueductal gray. The cartography of nicotinic receptors in the normal human brain will hopefully be of use in the study of the alteration of these receptors in diseased brain.