This review by Attia et al summarizes data from published studies on the rate of deep vein thrombosis (DVT) and the efficacy of thromboprophylaxis among general medical-surgical, trauma, neurosurgical, and spinal cord injury patients. Low-dose, unfractionated subcutaneous heparin appears to provide adequate DVT prophylaxis in medical and surgical patients in the intensive care unit, but may be less efficacious than subcutaneous low–molecular weight heparin in those who have sustained major trauma with skeletal injury. Mechanical prophylaxis, such as graduated compression stockings or pneumatic compression devices, has not been well investigated in either of these populations, but offers some benefit among neurosurgical patients. Studies of patients with spinal cord injury are too disparate to arrive at any meaningful conclusions. Decisions about prophylaxis against DVT must balance the absolute risk of venous thromboembolism against that of hemorrhage; thus, the efficacy data established in one population do not necessarily translate into a net benefit among other individuals.