Summary1. The decrease of the average bleeding time studied by Prof. Roskam and the increase of the clotting power of the blood after intravenous or intramuscular injection of thrombin allow to consider thrombin as a powerful product in hemorrhagic states.2. The absence of incoagulability after defibrination and the absence of intravascular thrombosis with normal doses of thrombin allow its use by parenteral way.3. The horsethrombin has not yet caused any immunity accident. It is not necessary to use human thrombin which is much more expensive.4. The intravenous injection of average doses of thrombin is an emergency therapy. Certain technical precautions (use of two needles and slow injection) should be taken. These are not necessary in case of intramuscular injection.5. Those injections have not any utility in case of afibrinogemia or fibrinopenia.