['To determine the risk of postoperative hemorrhage during a 3-year period of early postoperative administration of nadroparin (Fraxiparin) plus compression stockings in a large cohort of patients who underwent spinal surgery.', 'A total of 1,954 spinal procedures at different levels (503 cervical, 152 thoracic and 1,299 lumbar), performed between June 1999 and 2002 at the Department of Neurosurgery, Johann-Wolfgang-Goethe University Frankfurt, were included in this study. To prevent venous thromboembolic events (VTE), all patients were routinely treated subcutaneously with 0.3 ml of early (less than 24 h) postoperative nadroparin calcium (Fraxiparin) (2850 IU anti-Xa, Sanofi Winthrop Industrie, France) plus intra- and postoperative compression stockings until discharge. The occurrence of a postoperative hematoma (defined as a hematoma requiring surgical evacuation because of space occupation and/or neurological deterioration) and a deep venous thrombosis (DVT) were recorded in a database and analyzed retrospectively.', '13 (0.7%) of the 1,954 spinal operations were complicated by major postoperative hemorrhages. In 5 of the 13 patients (38.5%) the hemorrhage occurred on the day of surgery before the administration of nadroparin. Thus, the hemorrhage rate of patients receiving nadroparin was 0.4% (8/1,949). Ten (77%) of the 13 patients with major postoperative hematoma showed a progressive neurological deficit, which resolved in 6 patients and resulted in a hematoma-related morbidity of 31% (4/13). Only 1 patient (0.05%) in this series developed a clinically evident DVT, and none of the patients suffered from pulmonary embolus during the hospital stay.'] Is postoperative nadroparin administration for prophylaxis of thromboembolic events associated with an increased risk of hemorrhage after spinal surgery?