Background: Angiotensin II (Ang II) stimulates the expression of tissue factor (TF) and plasminogen activator inhibitor type-1 (PAI-1) and AT1 receptor blocker (ARB) reduced PAI-1 and TF activities in cell culture and rat model studies. We investigated the effects of ARBs on TF activity and PAI-1 antigen levels and compared the effects of ARBs in mild to moderate hypertensive patients. Methods: We administered placebo, losartan 100 mg, irbesartan 300 mg, and candesartan 16 mg daily during 2 months to 122 patients. This study utilized randomized, double-blind, placebo-controlled design. Results: Compared with placebo, ARBs significantly improved the percent flow-mediated dilator response to hyperemia (p=0.019 by ANOVA) with no differences among each. Compared with placebo, ARBs significantly reduced TF activity (p<0.001 by ANOVA) and candesartan therapy reduced to the greatest extent. Compared with placebo or losartan, irbesartan and candesartan therapies significantly lowered plasma levels of PAI-1 antigen (p<0.001 by ANOVA) with no differences between both. There were significant inverse correlations between the degree of changes in flow-mediated dilation and TF activity or PAI-1 antigen levels following ARBs therapies (r=-0.227, p=0.029 and r=-0.362, p<0.001, respectively). Of interest, there were significant correlations between the degree of changes in TF activity and PAI-1 antigen levels following ARBs therapies (r=0.458, p=0.000). Conclusions: We observed that ARBs significantly improved the percent flow-mediated dilator response to hyperemia and reduced TF activity and PAI-1 antigen levels in hypertensive patients. The clinical significance of different vascular effects among ARBs should be investigated.