The aim of the study was to determine if prophylaxis with multiple low doses of porcine surfactant would increase survival, without bronchopulmonary dysplasia, compared with rescue therapy, for respiratory distress syndrome in newborns of 25-31 weeks' gestation. Compared with rescue therapy (n = 122), prophylaxis (n = 134) decreased the need for oxygenation and ventilatory support within 3-72 h. It did not, however, increase survival without bronchopulmonary dysplasia (60% versus 46%) (odds ratio (OR) = 1.53, 95% confidence interval (CI) = 0.90-2.61). Furthermore, prophylaxis decreased the incidence of severe peri-intraventricular haemorrhage (3% versus 16%) (OR = 0.28, 95% CI = 0.09-0.84) and retinopathy of prematurity (2% versus 11%) (OR = 0.18, CI = 0.04-0.78). We conclude that prophylaxis did not increase survival without bronchopulmonary dysplasia. The decreased incidence of severe peri-intraventricular haemorrhage and retinopathy of prematurity after prophylaxis requires further study.