OBJECTIVES: The objective was to demonstrate the cost-effectiveness of a new absorbable hydrogel used in craniotomies compared to the option “do nothing” in France. METHODS: A Markov model was fed with clinical data from Grotenhuis and al. (Surg. Neurol. 2005;64:490-3) and with cost data from the French cost database (2006 data based on DRG (GHM) 01C04V  craniotomy without complication and 01C04W  craniotomy with complication). The model was run with three stages (T0: date of surgery; T1: 1-month follow-up; T2: 3-month follow-up) and three states (no CSF leak; CSF leak; death). The effectiveness outcome measure was a utility index given to each state based on the hypothesis that utility was 1 for “no CSF leak”; 0.5 for “CSF leak” and 0 for “death”. RESULTS: When hydrogel was used, the probabilities were for no CSF leak 1.000 at T0; 0.936 at T1 and 0.876 at T2; for CSF leak 0.000 at T0; 0.043 at T1 and 0.082 at T2; and for death 0.000 at T0; 0.021 at T1 and 0.042 at T2. When no hydrogel was used, the probabilities were for no CSF leak 0.060 at T0; 0.876 at T1; 0.767 at T2; for CSF leak 0.940 at T0; 0.103 at T1 and 0.191 at T2; and for death 0.000 at T0; 0.021 at T1 and 0.042 at T2. The cost-effectiveness ratio was €4,720.20 at T0; €5,174.29 at T1 and €5,645.06 at T2 when hydrogel was used and it was €27,693.48 at T0; €14,251.71 at T1 and €12,638.00 at T2 when hydrogel was not used. The ICER, which represents the additional cost necessary to gain one additional utility unit, was €9857.12. CONCLUSIONS: The strategy with hydrogel was more cost-effective than the strategy without hydrogel.