Extremely low birth weight (ELBW) is associated with impaired neurodevelopmental outcome in infancy. Information on the long-term cognitive and neurological consequences of ELBW is scarce. We aimed to identify the perinatal and neonatal factors of ELBW infants associated with adverse cognitive and neurological outcome at school age. A regional cohort of 135 ELBW infants born between 1993 and 1998 was prospectively evaluated at 3, 6, 12, and 18 months postmenstrual age and at yearly intervals up to age 10 years. The comprehensive follow-up programme for high-risk infants included neurological examinations and psychometric evaluations. According to the overall results of these tests, children were classified as either being normal or having minor or major impairment. At a mean age of 8.4 (SD: 1.6) years, 43% of children had survived without any impairment. Minor impairment was diagnosed in 39% and major impairment in 18% of assessed children. The proportion of disabled school children rose with decreasing gestational age. The following neonatal complications were significant risk factors for developing major or minor impairment at school age: an increase in head circumference < 6 mm per week (OR 4.0, 95% CI: 1.1-14.8), parenteral nutrition > or = 6 weeks (OR 2.5, 95% CI: 1.1-6.0), and mechanical ventilation > 14 days (OR 2.3, 95% CI: 1.0-5.1). High-grade intraventricular haemorrhage (IVH) and/or PVL (OR 13.3, 95% CI: 4.0-44.9), neonatal seizures (OR 5.2, 95% CI: 1.2-22.4) and bowel perforation, and/or necrotizing enterocolitis (OR 4.4, 95% CI: 1.1-17.0) were significant risk factors for developing major impairment. In spite of the relatively large proportion of normal children, ELBW remains an important risk factor for neurodevelopmental impairment at school age. Thus, measures to prevent complications such as necrotizing enterocolitis, cerebral haemorrhage, and undernutrition remain important goals for neonatal intensive care.