Proliferative retrolental fibroplasia was documented by ophthalmoscopy and histopathological study in a 940-gm birth weight infant with severe cyanotic congenital heart disease who died at the age of 11 weeks. Arterial oxygen tensions usually considered to be pathologic were not noted in this infant and would appear to have been possible in view of the cardiac anomalies found during life and at autopsy. These observations indicate that retrolental fibroplasia may occur in immature infants in the absence of oxygen abuse.