Bilateral progressive essential iris atrophy, more advanced in one eye than in the other, occurred in a 24-year-old white man. Histopathologic examination of the iris from the eye with the more advanced iris atrophy disclosed no vascular abnormalities in that the vessels were patent and appeared normal except for accumulated perivascular connective tissue. Fluorescein angiographic examination of the fellow eye that was undergoing the earliest changes of iris atrophy failed to reveal any vascular abnormalities. However, tonographic examination indicated a markedly decreased outflow facility. There does not appear to be any vascular abnormality involved in the pathogenesis.