Patients having aortic stenosis are at an increased risk of acquiring shear stress induced thrombocytopenia, platelet dysfunction and consumption of Von Willebrand factor reflected by a decreased factor VIII assay. 40 patients were enrolled in our study while 20 normal individuals served as controls. Doppler echocardiography, platelet count, platelet function and factor VIII assay were done to all patients as well as to the control group. Patients were divided according to their transvalvular gradient and their aortic orifice area into mild, moderate and severe aortic stenosis. Results showed that patients suffering from severe aortic stenosis (valve area <1 cm 2 and/or transvalvular gradient > 40 mmHg) are more prone to develop thrombocytopenia, platelet dysfunction and decreased factor VIII with a higher percentage of decrease in all these parameters and an increased probability of affection of these parameters than patients having mild aortic stenosis (valve area >1.5 cm2 and/or transvalvular gradient < 20mmHg) or those having moderate aortic stenosis (valve area 1-<1.5 cm2 and/or transvalvular gradient 20-40mmHg).