From July 1991 to September 1992 the authors treated twenty-eight patients with proven adult respiratory distress syndrome (ARDS). In this paper five patients with ARDS accompanying septicaemia are presented. In this group of patients, elevated pulmonary artery pressure or pulmonary hypertension (PAH) could not have been caused by LV failure, as it was possible in remaining twenty-three patients with ARDS after open heart surgery, so the effect of prostaglandin E1 (PGE1) on pulmonary hypertension could be followed accurately. Moreover, ARDS after septicaemia carries the worst prognosis. All patients were admitted from other hospitals, they were intubated and mechanically ventilated. ARDS was diagnosed 4 to 7 days after the primary injury.