The central corneal endothelium of 73 intact eyes was examined using a specular microscope. The photographs obtained were analyzed with a computerized digitizer for determination of the shape and size of the individual cells. The endothelium of cases younger than 30 years of age was composed mainly of hexagonal cells, 70% of all cells. With increasing age, however, the proportion as well as the number of hexagonal cells decreased significantly, although they continued to constitute the majority, 58%, of cells in the endothelium of cases over 70 years of age. There was a positive correlation between age and the proportion of nonhexagonal cells. It appears that the original hexagonal pattern of endothelial morphology is gradually lost with age, concurrent with a gradual increase in both mean cell size and variation in cell size.