Snake venom proteases, in addition to their contribution to the digestion of the prey, affect various physiological functions. They affect platelet aggregation, blood coagulation, fibrinolysis, complement system, blood pressure and nervous system. This review provides a ready reference for serine proteases that interfere in blood coagulation and fibrinolysis. They exhibit their activity by activation of specific zymogens of coagulation factors. These serine proteases serve as tools to study molecular details in the activation of specific factors involved in coagulation and fibrinolytic cascades and are useful in treating various thrombotic and hemostatic conditions.