A birth cohort of 12,058 infants was followed up to 14 years of age. Cerebral palsy, epilepsy, severe hearing defects, mental retardation and educational subnormality all had a higher incidence among the 411 children with a low birthweight (less than 2500 g). 6 per cent of the total cohort had educational problems with or without some other neurological handicap, and there was a higher prevalence among low-birthweight infants. 1.5 per cent had a handicap but normal school performance. Children with birthweight 1500 to 2499 g had a significantly higher percentage of handicaps than those of heavier birthweight. All the neurological handicaps were more common among boys than girls, but only in mental subnormality was there a marked difference. Height at 14 years was significantly less among low-birthweight children.