Serial sectioning of the locus coeruleus (LC) was employed to determine a topographic loss of nerve cells in patients with Alzheimer's disease (AD). Heaviest loss of nerve cells occurred in the central part of the LC which is thought to project to the temporal cortex and hippocampus, whereas least loss of cells occurred in the most rostral and caudal parts, thought to project to frontal and occipital regions of cortex, respectively. Such changes suggest that the primary damage to these nerve cells in AD occurs within their terminal fields and that perikaryal loss follows as a secondary retrograde change.