In a study of 150 consecutive patients with age-related macular disease and unilateral visual loss, the drusen in the better eye were analyzed for size, number, density, and fluorescein angiographic appearance, and these characteristics were compared with the type of the lesion causing visual loss in the contralateral eye. In the fellow eye of an eye with avascular detachment of the retinal pigment epithelium, the drusen were more densely packed, larger, and less fluorescent than in the fellow eye of an eye with primary neovascularization. The characteristics of drusen in fellow eyes of those eyes with pigment epithelial detachments and evidence of subpigment epithelial new vessels were intermediate between the other two groups. Because there is significant symmetry of drusen between fellow eyes, these data imply that the characteristics of drusen are important in the determination of the form of the lesion complicating age-related macular disease.