Primary Pulmonary Hypertension (PPH) is a rare disease that progressively increases pulmonary arterial pressure and pulmonary vascular resistance to the point of right heart failure, in the absence of secondary causes of the disease. The following specific risk factors that can trigger PPH have been identified and examined: appetite depressant drugs, oral contraceptives and hyperuricaemia. Familial PPH transmitted by an incomplete penetrance dominant autosomic mechanism is responsible for about 6% of PPH cases. Recent research groups have identified the gene responsible for familial PPH. Since pulmonary vasoconstriction is the prime cause of PPH, vasodilation of the pulmonary arterial circulation system (using prostacyclin in the form of epoprostenol or iloprost) is the main aim of treatment.