Platelet contractile force (PCF) is used as a surrogate marker of thrombin generation. PCF generation occurs concomitant with the burst of prothrombin fragment F 1null2 release. The time between assay start and PCF onset is identified as the thrombin generation time (TGT), and is used in assessing risk of bleeding, in diagnosing various disorders, and in monitoring the effects of pharmaceutical and other treatments. TGT is prolonged in clotting factor deficiencies and in the presence of direct and indirect thrombin inhibitors. TGT shortens to normal with clotting factor replacement and shortens with administration of rVIIa. TGT is short in thrombophilic states such as coronary artery disease, diabetes and thromboangiitis obliterans and prolongs toward normal with oral and intravenous anticoagulants.