Primary Pulmonary Hypertension (PPH) is a rare disease of unknown aetiology that is diagnosed only when the underlying causing factors are undetermined. Usually is discovered in its late stage, when pulmonary vascular resistances are severely compromised and the pathologic changes already well developed, resulting in right heart failure and death within several years of the onset of symptoms. The data published in the last years have provided new insights into the disease knowledge. In this article currents concepts about aetiology, pathogenesis and open lung biopsy value are reviewed; clinical manifestations and diagnostic methods are described; the usefulness of medical treatment to improve quality of life in these patients, mainly anticoagulation and vasodilator therapy with high-dose nifedipine, and how lung transplantation has increasingly become an option for selected patients with PPH, is also analysed.