Hemostasis is critically important in all operative procedures. Except for cardio-pulmonary support, control of hemorrhage takes priority over all other surgical goals. The surgeon must be familiar with techniques to control both diffuse coagulopathic bleeding and problems of local hemostasis. Generally, diffuse intraoperative bleeding (coagulopathy) does not occur if platelet counts are greater than 50,000 and PT/aPTT are less than 1.5 times control values. When intraoperative bleeding does occur, the astute clinician usually knows the specific cause responsible and the measures needed to arrest the bleeding.