The ultrastructural features of three surgically excised idiopathic subfoveal neovascular membranes were examined. Ultrastructural features of the cellular components in the membranes included retinal pigment epithelium, endothelial-lined vascular channels, photoreceptor cells, macrophages, myofibroblasts, glial cells, erythrocytes, and ghost erythrocytes. Extracellular constituents included 200-nm to 250-nm collagen fibrils, 100-nm collagen fibrils and fibrin. The findings in this study are consistent with previously reported findings of subfoveal neovascular membranes in age-related macular degeneration and the ocular histoplasmosis syndrome, with the exception of the presence of basal laminar deposit in membranes from age-related macular degeneration.