Two cases of respiratory syncytial virus pneumonitis in adults area described. In both patients, the clinical picture of the adult respiratory distress syndrome, with marked tachypnoea. hypoxaemia and bilateral diffuse pulmonary infiltrates, was present. One patient had systemic lupus erythematosus, while the other had chronic obstructive lung disease and was a heavy drinker of alcohol. Both patients survived and recovered after a prolonged stay in hospital.