Intracellular structures probably representative of mitotic figures were seen by specular microscopy in the endothelium of a corneal graft following a rejection reaction. Serial measurements over an eight month period initially showed grossly enlarged cells and apparent mitotic figures. Subsequently, clusters of cells smaller than any cells previously seen were observed. Measurements of endothelial cell area over this period demonstrated a highly significant (P less than 0.0001) decrease in cell area, or increase in cell density, with time. These observations indicate that at least under some circumstances mitosis occurs in the endothelium of the adult human cornea.