Background: Angiotentsin receptor blockers (ARBs) are known to have beneficial effects on cardiovascular, metabolic parameters in addition to blood pressure (BP) control. The aim of this study is to compare those effects of telmisartan and valsartan in patients with uncomplicated hypertension. Methods: The fifty-two subjects with uncomplicated hypertension (34 male; mean age 48.2 짹 8.7 years) were randomly assigned to take either telmisartan (80mg/day, n=26)- or valsartan (160mg/day, n=26)-based regimens for 12 months. Their anthropometric, laboratory, vascular, and echocardiographic data were measured at the baseline and the study end. Results: Baseline characteristics were not significantly different between the two groups except carotid-femoral pulse wave velocity (cfPWV, telmisartan vs. valsartan; 8.33짹1.54 vs. 7.32짹1.08 cm/s, p=0.012) and carotid intima-media thickeness (IMT, 0.73짹0.13 vs. 0.64짹0.13 mm respectively, p=0.01). Systolic and diastolic BP were significantly decreased in both groups at the study end and the changes were not significantly different between the two. Compared with baseline, telmisartan group achieved significant reductions in cfPWV (-11.2%, p=0.011), IMT (-9.7%, p=0.001) and increased flow mediated dilatation (+30.6%, p=0.002) at the study end, while valsartan group did not. In echocardiographic parameters, early diastolic mitral inflow velocity (E), early diastolic tissue Doppler velocity (e���) and E/A ratio were significantly increased only in telmisartan group (all, p<0.02). When compared the degree of changes of each variable between two groups, there was a more significant reduction in IMT (p=0.008) and a trend for increase in E velocity (p=0.059) in telmisartan group as compared with valsaltan group. Conclusions: In uncomplicated hypertensives, our findings suggest that telmisartan treatment appears to have more favorable effects on vascular structure and function and on cardiac diastolic function than valsartan treatment despite of similar BP reduction after 12 months. Further larger study will be needed to find out the difference of clinical outcomes of each ARB. Keywords: hypertension, angiotensin receptor blocker, telmisartan, valsartan