The pathogenesis of Best's macular dystrophy (BMD) is poorly understood. Previous histopathologic descriptions of BMD have been published in the literature; however, all were from elderly persons who clinically exhibited late manifestations of the disease. In this article, light and electron microscopic observations of an earlier stage of BMD are reported. Both globes were from a 28-year-old patient who had a "scrambled egg" lesions in the macula with some features of a pseudohypopyon. Our studies indicate that BMD is a generalized retinal pigment epithelial (RPE) abnormality that results in an abnormal accumulation of lipofuscin granules. Lipopigment accumulates within the RPE, within macrophages in the subretinal space, and within the choroid. These observations help to explain the clinical appearance as well as the fluorescein angiographic and electrophysiologic findings of this conditions.