Seventeen infants with extensive cystic leukomalacia without associated intraventricular hemorrhages were compared with 34 infants with normal cranial ultrasound findings and 34 infants with large intraventricular hemorrhages to establish whether different risk factors could be elicited for these lesions. Adverse obstetric factors that were associated with extensive leukomalacia were the place of birth (outborn [ie, not born at our hospital but transferred here after delivery]) and the need for emergency cesarean section. Neonatal risk factors, with the exception of gestational age, were equally distributed between the infants with the two types of lesions. The results of this study suggest that extensive cystic leukomalacia and large hemorrhages have similar predisposing factors, but the type of lesion that develops depends on the maturity of the infant.