Objective: to evaluate the effect of hemodynamic stress on the functional activity of von Willebrand factor (VWF) in vitro and to assess the potential of these data for predicting thrombus formation during testing of blood-contacting medical devices. Materials and methods. Fresh human platelet-rich plasma (PRP) was used in all experiments. Hemodynamic conditions mimicking vascular stenosis were simulated in a closed-loop system equipped with a peristaltic pump using a narrow channel (diameter 0.7 mm), generating shear rates (γ) of 1000, 3000, and 5000 s–1. Control experiments were performed under low-shear conditions in a wider channel (diameter 3 mm). von Willebrand factor activity (vWF Act, %) was measured after one and two circulation cycles. Results. Under control conditions, the reduction in VWF activity was minimal, decreasing to 69.2% after two circulation cycles. In stenosis-like channels, a pronounced decrease in VWF activity was observed, with the magnitude depending on shear rate: 65.1% at γ = 1000 s–1, 63.6% at γ = 3000 s–1, and 62.6% at γ = 5000 s–1. The most substantial decline occurred after the first passage through the stenotic segment. At the highest shear rate (γ = 5000 s–1), microscopic analysis revealed the formation of platelet aggregates. Conclusion. The study demonstrates that increasing shear rate leads to enhanced activation and proteolytic degradation of VWF, primarily due to the loss of high-molecular-weight multimers. These findings highlight the critical role of hydrodynamic conditions in the development of hemostatic disturbances associated with vascular stenoses and mechanical circulatory support systems. Incorporating the assessment of VWF activity and multimer distribution into testing protocols for vascular prostheses and extracorporeal devices may improve prediction of their hemocompatibility.