The authors measured changes in pulmonary and systemic haemodynamics in seven patients following oxygen inhalation, nifedipine and Ketanserin administration. A significant decrease in mean pulmonary artery pressure, cardiac index and heart rate could be observed following 30-min oxygen inhalation. No significant changes were found in pulmonary haemodynamics 1 hour after sublingual administration of 20 mg Corinfar (nifedipine). Long-term treatment (6 months) with Corinfar (30-60 mg per day) was not followed by a significant change in mean pulmonary artery pressure. However, in 3 patients a decrease in mean pulmonary artery pressure (6-11 mmHg) could be observed. Ketanserin (10 mg intravenously) did not significantly change the mean pulmonary artery pressure in patients with hypoxic pulmonary hypertension.