Abstract: Objective To explore the risk factors of the complication of pulmonary arterial hypertension(PAH) among Tibetan patients with congenital heart disease(CHD) at high altitude.Methods We retrospectively analyzed the composition of 115 PAH patients who were identified from 220 Tibetan CHD inpatients in Qinghai Cardiovascular Hospital during Jan 2007 to Dec 2009 and analyze the risk factor of PAH in different type of CHD.Results Among the 220 CHD patients,115(52.27%) had PAH.PAH was found in 64.65% of atrial septal defect(ASD),which was significantly both higher than 41.56% of the patients with ductus arteriosus(PDA) (χ²=9.312,P< 0.005) and 43.18% of ventricular septal defects (VSD) (χ²=5.763,P< 0.05).In all CHD-PAH patients,systolic pulmonary arterial pressure(sPAP) of the VSD-PAH group was significantly higher than that of other two groups(F=15.751,P< 0.05).In the patients living at the altitude > 3 000 m,the incidence of ASD-PAH was higher than that of the other patients(F=10.79,P< 0.05).How ever,the sPAP of the ASD-PAH group was lower than that of the PDA-PAH group(t=8.45,P< 0.05) and VSD-PAH group(t=24.26,P< 0.05).Age(odds ratio (OR)=1.31,P< 0.05),abnormal cardiac channel size(OR=1.15,P< 0.05),and altitude (OR=2.75,P< 0.05) were positively associated with an unfavorable outcome in ASD patients.Meanwhile,abnormal cardiac channel size was the only positive factor in PDA and VSD patients(OR=1.15-1.82,P< 0.05).Conclusion The incidence of CHD-PAH among Tibetan liveng in high altitude areas was 52.27%,which was obviously higher than the ones reported in the world.Hypoxia at high altitude is an important factor for development of PAH in ASD patients.