The histopathologic features of 176 eyes from 115 patients with senile macular degeneration have been studied. The results support the view that older persons with drusen are predisposed to the development of serous detachments, areolar retinal pigment epithelial atrophy, and subretinal pigment epithelial neovascularization. Direct clinicopathologic correlation was accomplished in 11 cases. Serial sections through the macular lesions were prepared and studied in 45 eyes. Five eyes were studied with stepped-serial sections through the macula at 0.1 mm intervals. Two-dimensional map reconstruction of the macular lesion of eight eyes was performed. Electron microscopic study of Bruch's membrane was performed in five eyes. A flow chart illustrating the interrelationships of the various morphologic forms of senile macular degeneration is proposed.