Abstract: The present invention concerns methods for determining platelet medicated clot formation. Specifically, the invention provides a method for determining platelet-medicated clot formation in a blood sample comprising: (i) obtaining sample of blood, and optionally mixing same with an anti-coagulant in an amount effective to inhibit clot formation; (ii) in a vessel, mixing the sample with a minute amount of an initiator to obtain a mixed sample, the amount being effective to initiate coagulation; (iii) rotating the mixed sample inside the vessel, whereby shear forces are developed at the surface of said vessel in a manner and for a time sufficient to allow adhesion of platelets at the surface of said vessel; (iv) determining clot formation at the surface of said adherent platelets. The method has different applications, among others, for determining a coagulation disorder in a subject having a coagulation factor dysfunction.