Abstract：Two patients (patient 1, 78-year-old female; patient 2, 39-year-old male) received hemocoagulase for injection 4 KU once daily due to bleeding of left lower abdominal mass and traumatic shock, respectively. After 8 or 4 days of hemocoagulase treatments, fibrinogen levels in the 2 patients decreased (1.49 g/L decreased to 0.71 g/L in the patient 1; 2.01 g/L decreased to 0.52 g/L in the patient 2) and active bleeding appeared. It was considered that hypofibrinogenemia was caused by hemocoagulase for injection. Hemocoagulase for injection was stopped and blood plasma cryoprecipitate were given in the 2 patients. Five days later, the fibrinogen level in patient 1 was 2.01 g/L and abdominal ultrasonography showed no active bleeding in the left lower abdomen; the fibrinogen level of patient 2 was 3.44 g/L and the liquid from thoracic drainage tube turned to light red.