Periventricular leukomalacia, a major cause of neurologic disabilities in preterm infants, can be isolated or associated with intraventricular and periventricular hemorrhage. To determine the risk factors for isolated periventricular leukomalacia, we retrospectively studied the characteristics of all very low birth weight infants affected by isolated periventricular leukomalacia who were delivered over a 5-year period and compared them with a control group of very low birth weight infants, matched within 2 weeks for gestational age, with no central nervous system pathology, and born during the same period. In total, 20 affected infants were compared with 98 control infants. Neonatal sepsis caused by coagulase-negative Staphylococcus (P = 0.014) and neonatal seizure (P = 0.026) were associated with isolated periventricular leukomalacia only on univariate analysis. Three variables demonstrated statistically significant associations with isolated periventricular leukomalacia on both univariate and multivariate logistic regression analysis as independent risk factors: birth weight (odds ratio, 4.31; 95% confidence interval, 1.54-12.06; P = 0.005), early neonatal hypotension requiring combined inotropic therapy (odds ratio, 4.90; 95% confidence interval; 1.22-19.68, P = 0.025), and delayed surgical closure of hemodynamically significant patent ductus arteriosus beyond age 7 days (odds ratio, 1.20; 95% confidence interval, 1.06-1.35; P = 0.003).