Background and Objectives : Several studies have revealed that the angiotensin receptor blockers(ARBs) improve endothelial function and insulin sensitivity. 3-hydroxymethylglutaryl-CoA(HMG-CoA) reductase inhibitors, statins, have observed in many risk groups to have salutary effects on lipid profile and modulation of plaque biology. The purpose of present study is to evaluate additive effects of telmisartan(ARB) and Rosuvastatin(HMG-CoA reductase inhibitor) to endothelial function, insulin sensitivity and arterial stiffness in patients with essential hypertension. Subjectives and Methods : Thirty-nine patients with essential hypertension were to receive telmisartan, which was administered at doses of 80 mg once daily using an open-labeled, prospective protocol for 8 weeks. And then twenty of them were to continue telmisartan therapy alone and nineteen were to receive rosuvastatin at doses of 30 mg once daily added to telmisartan. The patients were examined at baseline, 8 weeks, 16 weeks to assess changes of flow mediated-vasodilation(FMD), QUICKI(quantitative insulin–sensitivity check index), HOMA(homeostasis model assessment), adiponection and pulse wave velocity(PWV). Results : Telmisartan therapy improved FMD(from 7.6짹3.5 to 9.0짹2.8 %, p<0.01) and baPWV(Rt 17.3짹3.1 to 15.9짹2.6, Lt. 17.5짹2.8 to 16.1짹2.6 m/sec, p<0.01) at 8 weeks. But, it was not changed in QUICKI, HOMA level, and plasma adiponectin(p=NS, respectively). At 16 weeks, FMD & PWV of both group did not increased(p=NS) compared to 8 weeks result. Conclusion : These results suggest that telmisartan is effective at improving endothelial function and arterial stiffness in patients with essential hypertension. But adding rosuvastatin to telmisartan have little additive effect on that.