Epidural vessel bleeding and decortication of bone during instrumentation and fusion of the vertebral column account for the majority of blood loss during spinal surgery. Factors predicting blood loss requiring transfusion include type of surgery (fusion, laminectomy, pedicle subtraction osteotomy, osteotomy), low preoperative hemoglobin, tumor surgery, number of spine levels involved and underlying cardiopulmonary disease. Factors likely to decrease blood loss include use of the Jackson table, hypotensive techniques, and use of tranexamic acid or epsilon-aminocaproic acid. In nontumor surgery, use of a “cell saver” to capture blood cells for reinfusion decreases requirement for transfusion. Monitoring for development of intraoperative coagulopathy includes testing prothrombin time/international normalized ratio, partial thromboplastin time, platelet count, and thrombin level.