An inherited recessive form of retinopathy has been discovered in the domestic fowl (rdd) which is characterized by progressive deterioration of the retina, culminating in blindness by sexual maturity. Morphologically, the condition is recognizable by abnormalities in both the retinal pigment epithelium and the neural retina. Gaps in the pigment epithelium which are first detected macroscopically at nine days of incubation become larger and more numerous until the time of hatching, then disappear during the subsequent week. Undulations in the outer nuclear, outer plexiform, and inner nuclear layers are obvious by 11 days of incubation. There is a marked reduction of photoreceptors at 18 days of incubation as compared to normal controls. After hatching, the thickness of the retina decreases with age, primarily due to cell loss from the photoreceptor region and inner nuclear layer. Detachment of the atrophic retinas generally occurs in adults, and is followed in some adults by granulation and ossification of the vitreous. Problems concerning the site of the lesion are discussed.