A follow-up was carried out on twenty-two children (thirteen of whom were newborn) who had been treated with porcine surfactant (Curosurf) for respiratory distress syndrome. All the infants were enrolled in the follow-up at different times after surfactant replacement to evaluate the clinical status and the incidence (if any) of respiratory disease, adverse drug effects and allergic conditions. Twelve of the twenty-two children treated completed the follow-up. Seven prematurely-born children died of endocranial haemorrhage; two children died of malignant development of the basal pathology (leukaemia). Treatment with pig surfactant appears to cause no allergic side effects. Skin and laboratory tests performed were negative.