Essential hypertension (EH) is characterised by increased thrombotic tendency and impaired fibrinolytic activity. However, exercise-induced changes in coagulation and fibrinolysis have not yet been clarified. We aimed at determining thrombotic and fibrinolytic activity during exercise in patients with EH pre and post treatment with an Angiotensin II receptor blocker. Study 1 consisted of 30 untreated hypertensive (UH) and 15 normotensive (NT) individuals. The UH individuals who received treatment were included in study 2 and were followed up after a 3-month treatment period with valsartan. Thrombin-antithrombin (TAT) complexes and human plasminogen activator inhibitor-1 (PAI-1) were measured as markers of coagulation and fibrinolysis, respectively, at baseline, immediately after a treadmill exercise test and 30 min later. In UH, TAT and PAI-1 levels were significantly increased immediately after peak exercise and decreased 30 min later, as compared with baseline levels. At all time points, UH exhibited significantly higher TAT and PAI-1 levels compared with NT. No significant changes of TAT and PAI-1 levels were observed in NT and in patients post treatment. Acute high-intensity exercise results in impaired thrombotic and fibrinolytic response in untreated patients with EH. Angiotensin II receptor blockade with adequate blood pressure control greatly improves exercise-induced changes in coagulation and fibrinolysis in EH.