To test the hypothesis that characteristics of perinatal infection are associated with long-term cognitive limitations among preterm infants, we analyzed data from 294 infants (142 females, 152 males) [les ]1500g birthweight and <37 completed weeks of gestation who were examined at age 9 years. We identified 47 children (20 females, 27 males) who had a non-verbal Kaufman Assessment Battery for Children (K-ABC) scale standard value below 70, i.e. more than 2 SDs below the age-adjusted mean. The 247 children (122 females, 125 males) with a score [ges ]70 served as control participants. Maternal nationality and education, and low gestational age were significantly associated with a K-ABC non-verbal standard value <70. Both neonatal brain damage (intraventricular hemorrhage) and long-term sequelae (cerebral palsy [CP], diagnosed at age 6 years) were significantly associated with a below-normal non-verbal K-ABC score. Maternal fever at birth was present in five cases (11%) and eight controls (3%; odds ratio 3.6, 95% confidence interval 1.1 to 11.4). Clinical chorioamnionitis and preterm labor and/or premature rupture of membranes (as opposed to toxemia and other initiators of preterm delivery) were also more common among cases than control participants. When adjusting for potential confounders such as gestational age, maternal education and nationality, and CP, the risk estimate for maternal fever remained unchanged (3.8, 0.97 to 14.6). We conclude that perinatal infection might indeed contribute to an increased risk for long-term cognitive deficits in preterm infants.