OBJECTIVES Dabigatran etexilate (DBG) is a new direct thrombin inhibitor which is administered orally at a fixed dose. Patients with renal impairment are thought to be at higher risk of bleeding during thromboprophylaxis, and lower doses are recommended in this population. EMEA has approved DBG at a standard dose of 220mg once daily (od), and at a lower dose of 150mg od for patients with moderate renal impairment. Recent economic analyses for the UK have demonstrated that DBG 220mg od is cost-saving when compared with the commonly used agent, enoxaparin 40 mg od, with comparable efficacy and safety. This analysis investigates the cost-effectiveness of DBG 150mg od for the prevention of venous thromboembolism (VTE) in patients with moderate renal impairment undergoing total hip arthroplasty (THA) or total knee arthroplasty (TKA) from the perspective of the UK National Health Service. METHODS DBG 150mg od was compared to enoxaparin 40mg od using a decision model. Relative risks for VTE and bleed events specific to patients with moderate renal impairment (creatinine clearance ³30 and <50 mL/min) were derived from sub-group analyses of the phase III DBG trials, RE-MODEL and RE-NOVATE. Probabilities of recurrent VTE and post-thrombotic syndrome were estimated from published longitudinal studies. RESULTS DBG was less costly than enoxaparin in TKR and substantially less so in THR, primarily due to differences in administration costs. VTE and bleeding rates were similar for DBG and enoxaparin; the probability of cost-effectiveness was 75% in TKR and 97% in THR at a willingness-to-pay threshold of £20,000 per quality-adjusted life-year. These results were robust across a range of sensitivity analyses. CONCLUSIONS Thromboprophylaxis with DBG 150mg od in patients with moderate renal impairment is cost saving compared to enoxaparin 40 mg od, with comparable efficacy and safety.