Deep vein thrombosis (DVT) and pulmonary embolism (PE) are common life threatening complications of acute myelopathy. Prophylaxis with low dose unfractionated heparin (LDUH) has been the standard of care. Studies suggest that low molecular weight heparin (LMWH) has superior efficacy, but advantages may be offset by higher expense. Since LMWH (enoxaparin sodium) became available, standard practice at our institution has been to treat all inpatients with myelopathy with LMWH. To examine the impact of this practice, all inpatients diagnosed with myelopathy and treated with LMWH were sequentially matched by diagnosis and compared in a retrospective review with inpatients treated with LDUH. In each group, 11 patients had traumatic injury, four had transverse myelitis, four had neoplasms and five had spinal stenosis. Characteristics of the LMWH/LDUH groups were: mean age - 48.5/50.4; spinal level - cervical 13/7, thoracic 9/12, lumbar 2/5; American Spinal Injury Association impairment scale - A, 8/9; B, 2/2; C, 8/5; D, 6/8. There were five DVTs and two PEs in five patients taking LDUH; there were no cases of DVT or of PE in the LMWH group (p=0.04, two-tailed chi-square test). Isolated DVTs occurred in two patients with traumatic injuries and in one patient with transverse myelitis; PE + DVT occurred in one patient with a primary and one patient with a metastatic tumor. All developed within 3.5 months of the onset of spinal dysfunction. One patient with a traumatic injury on ibuprofen and dexamethasone had a gastrointestinal hemorrhage while receiving LMWH. The cost of administration of LMWH was $24,499 compared with $5,700 for LDUH. The LDUH group spent a total of 57 days in an acute care facility, costing $57,000.00 and patients treated with LMWH spent nine days, costing $9,000.00. We conclude that treatment with LMWH was associated with a significant decrease in incidence of DVT/PE and an overall decline in health care costs of approximately $30,000 or approximately $1,250 per patient. (J Spinal Cord Med 1997;20:402-405)