The efficacy of olmesartan on fibrinolytic capacity has not been studied yet. Therefore, the aim of the present study was to investigate the efficacy of olmesartan on hemostatic/fibrinolytic status by measuring plasma level of plasminogen activator inhibitor-1 (PAI-1) and soluble thrombomodulin levels in patients with hypertension. Forty-two consecutive, newly diagnosed (25 women and 17 men with a mean age of 48 +/- 8 years) patients with untreated essential hypertension were included in the study. Olmesartan medoxomil (20 mg/day) was started and the patients were followed up for 6 months. Baseline biochemical variables, thrombomodulin, and PAI-1 levels were compared with the levels of these variables measured at the end of the 6-month follow-up period. After 6 months of treatment with olmesartan medoxomil, there was a significant reduction in systolic and diastolic blood pressure (from 159.5 +/- 10.9 to 134.6 +/- 12.7 mmHg and from 98.0 +/- 6.3 to 83.9 +/- 7.0 mmHg, respectively). Mean plasma PAI-1 and thrombomodulin levels were also significantly decreased (59.73 +/- 41.91 vs. 48.60 +/- 33.65 ng/ml, P=0.001 and 8.09 +/- 2.29 vs. 6.92 +/- 1.42 mu g/l, P<0.001, respectively). Olmesartan medoxomil decreased plasma PAI-1 and thrombomodulin levels after 6 months of therapy, indicating a favorable effect on fibrinolytic capacity in patients with essential hypertension. Blood Coagul Fibrinolysis 22:29-33 (C) 2011 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.