OBJECTIVE To explore the demographic characteristics and clinical features of patients with idiopathic pulmonary arterial hypertension (IPAH) in China. METHODS Between March 2007 and September 2010, IPAH diagnosis was confirmed by right heart catheterization in 150 adult patients from 31 clinical centers in China. Clinical and hemodynamic data were analyzed and patients were divided into WHO functional class I/II and WHO functional class III/IV group. RESULTS The mean age of 150 patients were 36 ± 13 years with female patient/male patient ratio of 2:1, and mean BMI was (21.3 ± 3.5) kg/m(2). Fatigue (n = 123, 82.0%) and dyspnea (n = 112, 74.7%) are the most common symptoms. Accentuated pulmonic second sound (P(2)) was detected in 92.0% (n = 138) of patients during physical examination, which was also the most common sign. About 49.0% (n = 73) patients were WHO functional class I/II patients and 46.0% (n = 68) patients were WHO functional class III/IV patients. Six minutes walking distance (6MWD) and Borg dyspnea score was (337 ± 101) m and 2.0 (2.0, 4.0), respectively. Right ventricular hypertrophy was suggested by ECG in 93.1% (n = 140) patients. Right atrial pressure was (10 ± 6) mm Hg, mean pulmonary artery pressure was (61 ± 16) mm Hg, cardiac index was (2.3 ± 0.8) L×min(-1)×m(-2) and pulmonary vascular resistance (1484 ± 699) dyn×s(-1)×cm(-5) in this cohort. 6 MWD (305 m ± 89 m vs. 377 m ± 88 m) was significantly shorter while Borg dyspnea score [3.0 (3.0, 5.0) vs. 2.0 (2.0, 3.0)] was significantly higher in WHO functional class III/IV patients than in WHO functional class I/II patients. Similarly hemodynamic parameters were also worse in WHO functional class III/IV patients than in WHO functional class I/II patients (all P < 0.05). CONCLUSION Idiopathic pulmonary arterial hypertension patients in this cohort affect mostly young adults, dominated by female gender and lower body mass index. Fatigue and dyspnea are the most common symptoms and accentuated pulmonic second sound (P(2)) is the most common sign. IPAH patients are often displaying severe functional and hemodynamic disturbance at first visit to hospitals. Dyspnea and hemodynamic impairment are related to 6MWD and WHO functional class.