A case of preretinal macular fibrosis, following long-standing central vein occlusion and hemorrhagic glaucoma, was examined macroscopically and electron-microscopically. Pretreatment with cyclodiathermy puncture was performed twice before enucleation. The following morphologic results were observed: 1. Epiretinal cell layers in the peripapillar and foveolar regions which caused no 'puckering' of the retinal surface. These cell layers were mainly composed of glial cells. Some Müller cell processes and macrophages were also present. The epiretinal glial cells stem from the surface of the papilla and of the retina. They leave the retina through breaks of the basal lamina (especially where the latter is only a thin layer). 2. Folding (puckering) of the retinal surface was exclusively observed under condensed masses of fibrous tissue. The epiretinal fibrous tissue is composed of immature collagen fibrils of various diameters, of acid glycosaminoglycans, and of granular deposits of long-spacing collagen. The fibrillar material is firmly attached to the basal lamina of the retina. Shrinkage of the epiretinal fibrous tissue similar to the shrinkage of scar tissue is assumed to be the reason for the development of traction to the retinal surface. The epiretinal glial cells are assumed to be the sites of synthesis of the preretinal fibrous masses and glycosaminoglycans.