Of 235 survivors who had taken part in a randomised trial of artificial surfactant and who were born in Cambridge, follow up information was available for 231 (98%) infants. In 12 cases information came from local doctors; all others were assessed at 9 and 18 months (n = 212) or 9 months only (n = 7). There was no difference between those who had been treated with surfactant and control babies in the incidence of neurological impairment, mental impairment, respiratory infections, allergies, or hospital admissions up to 18 months after full term. In those born before 30 weeks' gestation (where surfactant most improves survival) the number of surviving randomised children who were normal was 35 of 61 in the treated group (57%) compared with 25 of 61 in the control group (41%). Improved neonatal survival after prophylactic surfactant treatment is not associated with an increased incidence of neurodevelopmental impairment.