OBJECTIVES: Haemophilia patients with inhibitors characteristically have high annual drug costs and other health care related costs. There are essentially three treatment options: NovoSeven, FEIBA or ITT followed by regular F8 treatment. Aim: This cost-minimization simulation examines the treatment costs of NovoSeven versus FEIBA and ITT/F8 for haemophilia A/B patients with inhibitors. METHODS: The simulation is based on a standard set of assumptions for an average severe haemophilia patient. First, primary prophylaxis treatment is defined by daily treatment on an annual basis of 50 ìG/KG for NovoSeven and 40 IU/KG for FEIBA. ITT-F8 treatment follows the Bonn Protocol for ITT at 300 IU/KG followed by F8 at 15 IU/KG. Second, we assume 2 breakthrough bleeds per month. Third, the patients weight changes each year throughout a 21 year child-adolescent-manhood life cycle time series model according to average yearly weight changes for boys in the standard population. Fourth, costs are based on estimated average global realised wholesaler purchaser prices in EUROS. ITT-F8 costs 0.7271 EUROS for an IU/KG. FEIBA costs 1.143216 EUROS for an IU/KG. NovoSeven costs 0.9191 EUROS for an ìG/KG. Costs are also discounted at a rate of 3.5 percent a year over time. RESULTS: Annual N7 costs for a 70 KG patient are 990.662 EUROS per year. Annual FEIBA costs for a 70 KG patient are 1.168.367 EUROS per year. Annual ITT treatment is 11.146.504 EUROS and annual F8 treatment costs are 277.679 EUROS. CONCLUSION: Novo Seven is slightly cheaper compared to FEIBA for certain dosing regimens. NovoSeven is also cheaper than ITT-F8 for the first 6-7 years after treatment begins.