Objective:To investigate the demographic characteristics and the causes for pulmonary hypertension (PH) in adult patients.Methods:A total of 2 508 adult patients diagnosed as PH,who came from the Second Xiangya Hospital of Central South University from January 2010 to December 2014,were retrospectively investigated.All subjects underwent the clinical diagnosis,or the echocardiographic diagnosis,or thetraditional hemodynamic criteria by right heart catheterization (RHC).The patient's data including hospital numbers,gender,ages,primary diseases,etc,are collected and analyzed.Results:In this study,the number of patients diagnosed as PH was increased year by year.The median age of 2 508 patients was 47 (18-93) years old,and there were 933 males (37.2％),the ratio of male to female was 1:1.69 (P＜0.05).Female was more common in Class Ⅰ PH (pulmonary arterial hypertension) and Class Ⅱ PH (pulmonary hypertension due to left heart disease)(＞70％),but there were more male patients (74.5％) in Class Ⅲ PH (pulmonary hypertension due to lung diseases and/or hypoxia).In our study,896 cases (35.73％) were the Class Ⅰ PH,1 163 cases was the Class Ⅱ PH (46.37％),411 cases was the Class Ⅲ PH (16.39％),and the Class Ⅳ PH (chronic thromboembolic pulmonary hypertension) and the Class Ⅴ PH (PH with unclear and/ or multifactorial mechanisms) were diagnosed in 32(1.27％) and 6 patients (0.24％),respectively.The diseases with largest number of patients for the top 7 primary PH were rheumatic heart disease (1 090,43.48％),congenital heart disease (692,27.60％),chronic obstructive pulmonary disease (358,14.28％),connective tissue related disease(156,6.22％),valvular heart disease (66,2.63％),idiopathic PH (46,1.83％) and pulmonary embolism (27,1.08％).Conclusion:Adult PH patients' peak incidence age is 41-50 years old.This disease is more common among women,and the Class Ⅰ/Ⅱ PH are common in women while the Class Ⅲ is more common in men.Rheumatic heart disease and congenital heart disease may be the most common cause for pulmonary hypertension in China,and chronic obstructive pulmonary disease is the most common cause for the Class Ⅲ PH,in which the patients are old.