Background and Objectives Currently, the quality of platelet (PLT) products is evaluated using a series of in vitro tests, which only analyse PLTs as an inspection material. However, it would be ideal to assess the physiological functions of PLTs under conditions similar to the sequential blood haemostatic process. In this study, we attempted to establish an in vitro system where the thrombogenicity of PLT products was evaluated in the presence of red blood cells (RBCs) and plasma using a microchamber under constant shear stress (600/s). Materials and Methods Blood samples were reconstituted by mixing PLT products, standard human plasma (SHP) and standard RBCs. Each component was serially diluted keeping the other two components fixed. The samples were applied onto a flow chamber system (Total Thrombus‐formation Analysis System T‐TAS), and white thrombus formation (WTF) was assessed under large arterial shear conditions. Results We observed a good correlation between the PLT numbers in the test samples and WTF. The WTF of samples containing ≦10% SHP was significantly lower than those containing ≧40% SHP, and no difference was observed in WTF among samples containing 40%–100% SHP. WTF significantly declined in the absence of RBCs, whereas no change in WTF was observed in the presence of RBCs, over haematocrit range of 12.5%–50%. Conclusion The WTF assessed on the T‐TAS using reconstituted blood may serve as a new physiological blood thrombus test to quantitatively determine the quality of PLT products.