Ocular fundi of 54 premature infants (age of gestation < 37 weeks) and 5 full-term babies with low body weight (< 2500 g) were examined at the forth week after birth. According to the international classification of retinopathy of prematurity, they were diagnosed as retinopathy of prematurity (ROP). The risk factors of the incidence of ROP were statistically analyzed, respectively. The results show that the lower the body weight, the shorter the gestation, the higher the oxygen concentration, the longer the oxygen administration, the higher the incidence of ROP. The incidences of ROP in the following baby groups, the body weight at birth < or = 1500 g, gestational weeks < or = 32 weeks, the oxygen concentration administered > 80%, and the duration of persistent oxygen administration > 5 days are significantly higher than those in the corresponding respective other groups. It is also demonstrated that the duration of the first time of oxygen administration and the complications of the newborn babies such as asphyxia, intracranial hemorrhage, anemia, pneumonia and blood transfusion have no effects on the incidence of ROP.