This paper reports an examination of the incidence of chronic lung disease in premature infants admitted to the neonatal intensive care unit at Liverpool Maternity Hospital. From January 1980 to December 1989 details were obtained for these infants such as gestation, weight, sex, survival to discharge and ventilatory support received. The findings show that a total of 242 infants had developed chronic lung disease; one-third of these were born in 1988 or 1989. Logistic regression suggests that chronic lung disease was significantly associated with being male, low birthweight, low gestation, surviving to discharge, and being born in 1988 or 1989. Among infants at 'high risk' of this condition, mortality had significantly decreased and the incidence had significantly increased. This increase is not fully explained by changes in the population admitted during the last decade. A rising workload should be anticipated in terms of the specialised follow-up and care required by these babies.