Iris specimens were obtained during trabeculectomy from 8 patients with capsular glaucoma. Serial sections for light and electron microscopies were prepared. By light microscopy, a three-dimensional model of the iris vessels accompanied by the pseudoexfoliation (PE) materials stained with toluidine blue was constructed. The PE materials attached to the vessel sometimes at a localized small area and sometimes along a certain length of the vessel; in some parts the vessel was free of the PE materials. By electron microscopy, the PE materials were seen to consist of fluffy fine filaments with the diameter of 20-30 nm and the length of 100-700 nm. They were accumulated underneath the vascular endothelial cells which showed a marked thinning and extended cytoplasmic processes. The accumulation of the PE materials produced a protrusion into the vascular lumen which was narrowed and sometimes completely occluded. The PE materials were mingled with the basement membrane which was displaced and sometimes disrupted. Some vessels surrounded by the PE materials showed marked endothelial degeneration, but some vessels free of the PE materials showed separation of the endothelial junctions leading to extravasation of erythrocytes. The endothelial cells and pericytes of the iris vessels as well as the stromal pigmented cells showed cytoplasmic indentations in which fine filaments with the diameter of 14-20 nm were present and were in close relationship with the cytoplasm at the bottom of the indentations, where the cytoplasmic membrane was indistinct. It was thought that these cells produced the PE materials, although established fine filaments of the PE materials could not be found within the cytoplasm.