A cohort of very low birthweight infants (less than 1500 g) born in 1979-81 from a geographically defined area was followed up, and a costing of the initial admission to the neonatal intensive care unit was made. A four point scale for the severity of disability was used and estimation of the costs of education and full time residential care was made and discounted at 5% over the appropriate period. During the three years a progressively increasing proportion of infants survived, and this was associated with an increasing proportion of disabilities among the survivors. If costs are related to outcome up to the age of 4 they get progressively less over the three year study period. After the age of 4 the costs of special education and residential care dominate, and the cost trend is reversed.