The Registry to Evaluate Early and Long-term PAH Disease Management (REVEAL) has been designed to meet the need for current information about patients with pulmonary arterial hypertension (PAH). The main objectives of REVEAL are to better define and understand PAH and to assess the consequences of treatment strategies. REVEAL is collecting clinically relevant data from 3500 consecutively enrolled patients with confirmed PAH diagnoses. Outcomes will be evaluated longitudinally and compared according to the baseline classification of PAH. The primary outcome for group comparisons will be survival. Collected data include World Health Organization functional class, 6-minute walk distance, cardiopulmonary exercise testing, pulmonary function test results, hemodynamic measurements, functional status, hospitalizations, and death. REVEAL will be the richest source of data on patients with World Health Organization group I PAH.