Objectives : The objective of this study was to assess the effect of acupuncture applied at the ST36 point on blood pressure and endothelial dependent vasodilation in hypertensive patients. Methods : 24 hypertensive patients were recruited and randomized to a study group (12 subjects) or a control group (12 subjects). Both groups took FMD (endothelial-dependant, flow-mediated dilation) measurement and then acupuncture needles were inserted at ST36 for the study group. In the control group, they took sham acupuncture as a control. FMD was rechecked after 10-min acupuncture treatment. Blood pressure was measured before and after acupuncture treatment. Results : FMD increased significantly in the study group after acupuncture (9.5${pm}$2.0% to 11.1${pm}$2.2%), but not in the control group. In both groups, there were no changes in blood pressure and heart rate. Conclusions : Acupuncture on ST36 appears to improve endothelial dysfunction of hypertensive patients and this might result from inducing activation of endothelium-derived nitric oxide.