This is a nationwide sampling study. To investigate the prevalence of primary aldosteronism (PA) in Chinese patients with hypertension, we will conduct a case detection of PA in Chinese hypertensive patients from 10 centers of China (including Beijing, Chongqing, Shanghai, Guangzhou, et al.); furthermore, a case confirmation of PA (captopril challenge test and saline infusion test) will be performed if the result of case detection is positive. This study will be completed in two years.