The authors have prospectively studied the incidence and nature of retinopathy of prematurity (ROP) in 159 consecutive preterm infants at an institution serving a predominantly black and Hispanic, low-income, inner-city population. Overall, ROP developed in 73 (46%) of the 159 patients. However, ROP developed in 54 (72%) of 75 patients with birth weight under 1200 grams. Significant high-risk factors observed were low birth weight (P less than 0.001), short gestation period (P less than 0.001), and extended supplemental oxygen administration period (P less than 0.001). Other significant factors were the presence of intraventricular hemorrhage (P less than 0.01) and respiratory distress syndrome (P less than 0.01). An additional factor observed to be significant for the development of severe ROP (stages III-V) was sepsis (P less than 0.01). Race and maternal history of substance abuse were not found to be significant factors. The unusually high incidence (72%) of ROP in low birth weight infants found in this study may be due to limited prenatal care and other maternal factors such as inadequate nutrition.