Using the current Nottingham Health District, England, as a geographically defined population we have investigated the changing patterns of neonatal respiratory diseases. We have categorized all newborns who developed a respiratory problem during either 1977 or between April 1, 1983, and March 31, 1984 using a system based on that of Hjalmarson (Acta Paediatr Scand 1981; 70:773-783). There has been no change in the incidence of any of the disease types. However, the gestation of babies in two groups, idiopathic respiratory distress syndrome (IRDS) and minimal respiratory disturbance (requiring added oxygen for less than 6 hours), has shown a significant reduction. Overall, mortality for infants developing IRDS has shown a slight decrease, and for infants between 29 and 32 weeks gestation, mortality has shown a significant reduction. Overall, requirements for oxygen therapy and ventilation have shown a threefold increase, while hours in receipt of continuous positive airways pressure (CPAP) have increased sevenfold.