Electron microscopic study showed the presence of macrophages in the retina in postnatal rat. These phagocytic cells were localized predominantly in the nerve fiber layer between the ganglion cells and the inner limiting membrane. They were pleomorphic, some displayed typical features of tissue macrophages bearing prominent cytoplasmic inclusions, others resembled monocytes or microglial cells. Their cytoplasm contained a variable number of electron-dense granules of size 0.15μm and these exhibited peroxidase activity.