Aim: Von Willebrand Factor is a glycoprotein, which plays role in primary hemostasis, mainly acts getting platelets to adhere onto the subendothelial tissue and carrying Factor VIII. Although vWF deficient animals had been shown to be resistant to atherosclerosis and thrombotic events, it had not been proven in humans. In this study, we aimed to investigate whether a relationship exists between VWF activity and therapeutic success of thrombolysis. Methods: The study was carried out on 40 patients who were administered thrombolytic therapy due to myocardial infarction and 30 healthy controls. Von Willebrand Factor activity was measured in plasma samples which were taken before the procedure. The results were compared between therapy effective and ineffective patients and controls. Results: Average vWF activity was 131.0±64.0% in patients whereas 113.9±47.7% in controls (p>0.05). On the other hand, mean VWF activities of 24 patients who achieved therapeutic success and 16 therapy failed patients were 103.9±58.9% and 171.7±49.0% respectively (p<0.01). Conclusion: In this study; we found that plasma vWF activity is among the factors affecting the outcome of thrombolytic therapy in patients with myocardial infarction so, it may be used to predict the therapeutic success of thrombolysis.