OBJECTIVE: Recent evidence suggests that low molecular weight heparin (LMWH) can be used as an alternative to oral anticoagulants in the prevention of recurrences after deep venous thrombosis (DVT). Our objective was to examine the clinical, economic and policy implications of LMWH instead of oral anticoagulants as secondary prophylaxis for DVT. METHODS: Fixed-effect model was used to conduct a meta-analysis of data about safety and effectiveness of LMWH from 4 trials. A decision tree was constructed using published data to simulate the outcomes and cost of care of patients receiving secondary prophylaxis with either LMWH or oral anticoagulants after a first episode of DVT. RESULTS: Meta-analysis showed that the OR for bleeding, DVT and pulmonary embolism were respectively 0.402 (0.153-1.057), 0.665 (0.22-2.013) and 0.462 (0.075-2.825). None of the three OR was significant, however, the upper limit of the 95% confidence interval around the estimate for bleeding was near to 1. When a cohort of 1,000 simulated patients with DVT received secondary prophylaxis with LMWH instead of warfarin 4.5 lives were saved, i.e. 22 additional days of life and 18 additional quality-adjusted days. Prophylaxis with LMWH cost $768 more than prophylaxis with warfarin, which is $15,360 per QALY saved. The results were sensible to the efficacy of LMWH in reducing pulmonary embolism: LMWH is no longer effective if patients incur 35% more episodes of pulmonary embolism than with warfarin. CONCLUSIONS: LMWH is a cost-effective drug to perform secondary prophylaxis after a thromboembolic episode. However, some critical issues need to be definitively ascertained before recommending it: first, the neat preventive efficacy of LMWH over warfarin need to be assessed by larger trials; second, patients preferences for oral or subcutaneous administrations are to be elicited.