We followed the clinical course of 29 eyes with geographic atrophy of the retinal pigment epithelium and identified three phases of the disease through which the eyes progressively evolved. In the initial phase, eyes showed focal discrete areas of atrophy of the retinal pigment epithelium in the parafoveal area. These eyes retained good visual acuity for many years. The second phase was characterized by foveal involvement in which there was a precipitous loss in visual acuity. Foveal involvement included coarse foveal granularity, thinning of the foveal retinal pigment epithelium, increasing encirclement of the fovea with focal areas of atrophy, and minimal macular drusen. The end stage of the disease was a confluent, usually circular, area of atrophy that involved the entire central macula.