Sixteen cases of essential iris atrophy and two of iris nevus (Cogan-Reese) syndrome were reviewed retrospectively by light and electron microscopy. Varying degrees of corneal endothelial proliferation onto the trabecular meshwork and anterior iris were seen in all cases. The demonstration of an endothelial-abnormal basement membrane complex on the anterior iridic surface, deep to synechias in over half the cases, indicates that endothelialization may be primary, since it precedes the formation of anterior synechias. Pathologic and clinical evidence suggests that the iris nevus syndrome, Chandler's syndrome, and essential iris atrophy represent a continuum of clinical manifestations of a single disease process involving proliferation of the corneal endothelial and characteristic iris abnormalities; the latter may be secondary to variations in the pattern, rate, and extent of endothelial proliferation. We suggest the term "proliferative endotheliopathy" to emphasize the common pathogenetic role of corneal endothelial proliferation in all three entities (iris nevus syndrome, Chandler's syndrome, and essential iris atrophy). A more succinct alternate term is "the iridocorneal endothelial (ICE) syndrome."