Primary pulmonary hypertension (PPH) is defined as continuing increase of the blood pressure in the pulmonary arteries without any known reason. The expected incidence in Western Europe is one to two per one million inhabitants, which in Denmark is around five to ten new cases each year. The diagnosis PPH is established by excluding other known reasons for secondary pulmonary hypertension. Primary pulmonary hypertension is a progressive and incurable disease. The treatment of PPH is with vasodilatory agents and anti-coagulants with supplementary diuretics, digoxin and oxygen as second-line of treatment. The most important vasodilators are calcium-antagonist and Epoprostenol (prostacyclin PGI2). Lung transplantation or combined heart and lung transplantation is at the moment the only possible treatment for progressive PPH disease in Denmark. The one year survival after lung- or heart and lung transplantation for PPH are not as good as the survival among other patients who are heart and lung transplanted.