Objectives : To report a case of the treatment of primary hypertension by Oryung-san (五?散: Wulingsan in Chinese, Goreisan in Japanese) monotherapy. Methods : The blood pressure (BP) fluctuation was checked of a woman who had sudden BP elevation without a history of hypertension treatment. There were no specific history of disease and results for the laboratory examination and image diagnosis including MRI. The woman was diagnosed with primary hypertension and she was given supple of Oryung-san extract (Hanpoong Pharm Co.) 3 g, three times a day for three months. The BP has been checked with digital sphygmomanometer (HEM-7111, Omron Japan) in brachial artery at home. Results and Conclusions : The patient had had stable BP since three weeks after Oryung-san treatment was initiated. There were no subjective symptoms, then Oryung-san medication also had quit after three months treatments. This shows some possibility to control hypertension using Oryung-san, which resembles thiazide that acts on the distal convoluted tubule and inhibit sodium-chloride reabsorption. For further evaluation of the effectiveness, well-designed randomized controlled trials should be undertaken.