The activation rates of Factor X in the intrinsic coagulation pathway and by RVV were measured in the stationary condition in a concentric cylinder device in a shear field and in a capillary flow reactor. The shear rates in the cylinder device were 70 and 140 sec−1 and the range of the flow rate in the flow reactor was from 0.59 to 1.20 cm3/min. The activation rates in the intrinsic pathway decreased with the increase of the shear rate and therefore with the liquid flow rate. On the other hand, the rate of activation by RVV did not vary in the shear field.