Abstract: Objective: To evaluate the haemostatic effect of hemocoagulase injection on the extraction of mandibular impacted wisdom teeth. Methods: Two hundred and sixty-seven cases were randomly divided into the experimental group (135 cases) and the control group (132 cases). The experimental group received the same extraction procedure as the control group, except a local injection of 1U hemocoagulase half an hour before the operation. Results: There was no bleeding case in the experimental group 40 minutes after the extraction, and 1 bleeding case after 24 hours. However, there was 5 bleeding cases 40 minutes after the extraction and 7 bleeding cases after 24 hours in the control group. Statistical analysis showed significant difference between two groups (P<0.05). Conclusion: Hemocoagulase injection before tooth extraction was effective on theh reducing of postoperative bleeding.