There are many risk factors contributing to retinopathy of prematurity (ROP). Some are still controversial, including the use of glucocorticoid and intraventricular hemorrhage. Hence, a retrospective study was performed to evaluate the association between the suspected risk factors and ROP in a medical center in southern Taiwan. One hundred fifty-nine infants with birth body weight < 1600 g admitted to our neonatal intensive care unit before the 29th day of life were enrolled into this study. Clinical data were analyzed by means of logistic regression. The prevalence of ROP in all infants (birthweight < 1600 g) is 36.48% (58 of 159) and 59.46% (22 of 37) in extremely low birthweight infants (birthweight < or = 1000 g). One infant with gestational age 32 weeks and birthweight 1420 g developed stage III ROP. Logistic regression revealed six factors to be significant variables. Birthweight < or = 1000 g, intraventricular hemorrhage, sepsis, and use of glucocorticoid or dopamine were risk factors associated with higher incidence of ROP. Supplementation of vitamin E was shown to relate to lower incidence of ROP. This study confirms several risk factors recognized in previous statistical analyses. Sepsis is the most significant factor contributing to ROP. Vitamin E was proven to be effective in prophylaxis of development of ROP. The possibility of development of ROP could not be excluded in infants with gestational age > 32 weeks.