A model was experimentally made with 2 hours serial infusion of thromboplastin (Tp) into rabbits to examine the drug's effect on a hemorrhagic tendency and to elucidate the coagulation and fibrinolytic system in acute DIC encountered in obstetrics, and the system was periodically observed. Groups given the drug, given it during pregnancy, those which bled massively, and those with accelerated fibrinolysis were prepared. The results are as follows. 1) Fibrinogen, PT, APTT, TEG, ELT, AT-III, antiplasmin activity, and platelet count varied markedly from the initiation of Tp injection, and returned to normal following termination. 2) Blood from the heparin dose group showed non-coagulation but decreases in the platelet count and fibrinogen were inhibited. 3) In the aprotinin dose group, serial 2 hour administration induced inhibition of fibrinolysis despite the relatively delayed appearance of anti-fibrinolytic activity. 4) No fibrinolytic effects were seen in anti-plasmin activity or ELT in the tranexamic acid dose group. 5) Lowering of parameters examined was marked in the Tp dose group during pregnancy. 6) The mortality rate up to 6 hours after Tp infusion was 54.5% with solely given, and 10% with group given drug. 7) Death within one hour of Tp infusion in the mass bleeding group, being rated for 50%, was improved to 16.7% by the pre-administration of urokinase.