The clinical, histological and ultrastructural findings in a case of Cogan-Reese syndrome (iris nevus) are presented. The typical iris nodules first appeared 14 years after a unilateral, juvenile, open-angle glaucoma was diagnosed. No lasting regulation of the intermittently elevated pressure was possible either medically or surgically. The failure of two filtering operations was due to the histologically verified endothelialization of the blebs. Endothelialization and deposition of Descemet's membrane on the anterior surface of the lens and on the zonule is described for the first time in this syndrome. The histological findings support the view that the peripheral anterior synechiae and iris nodules are secondary to the endothelialization. Hence the diagnosis of Cogan-Reese syndrome cannot be made until relatively late in the course of this disease. Cytological similarities between the proliferating endothelium in this case and in Chandler syndrome support the recent hypothesis that the Cogan-Reese syndrome belongs to the irido-corneal-endothelial group of syndromes.