In France, the incidence of invasive meningococcal disease (IMD) is assessed through the mandatory reporting system (MRS). The completeness of the system is regularly evaluated using capture-recapture analysis to adjust incidence rates and monitor trends. The National Reference Center (CNR) for Meningococci receives invasive meningococcal strains from all bacteriology laboratories. The surveillance network for invasive bacterial infections (Epibac) collects data on cases involving the isolation of meningococcus in blood or cerebrospinal fluid (CSF). A three-source capture-recapture analysis (DO, NRC, Epibac) was used to estimate the completeness of each of the three sources for the year 2005. The analysis focused on cases in which a meningococcal strain was isolated from blood or CSF, a criterion common to all three systems. Due to limited national coverage, the completeness of the Epibac network was estimated based on cases admitted to hospitals that were actively participating in the Epibac network in 2005. Interdependencies between the sources were investigated by cross-referencing the sources in pairs (Wittes method). Log-linear models were used to estimate the number of cases not recorded in any of the sources. A comprehensive approach was first taken, followed by stratification by age, serogroup, and region. In 2005, 627 cases of MII confirmed by culture in blood and/or CSF were reported in at least one of the three sources (DO=588, CNR=481, Epibac=425). Dependencies between the CNR and the DO and between the CNR and Epibac were identified. The total estimated number of IIM cases in 2005 was 639 [95% CI=630–656]. The coverage rate of the DO was estimated at 92% [95% CI=90–93], and that of the CNR at 76% [95% CI=75–77]. The coverage rate within the Epibac network was estimated at 82% [95% CI=80–83]. Stratified analyses revealed lower coverage for serogroups other than B and C, as well as higher coverage for children under 4 years of age. The results of this analysis showed a clear improvement in the coverage of the DO and the Epibac network in 2005 compared to a previous assessment in 2000 (73% for the DO and 57% for Epibac), while that of the CNR remained stable. The high level of coverage of the DO for IIM confirmed by culture in 2005 should lead to regular monitoring of this coverage to rule out a possible decline in the coming years. It must also take into account changes in practices regarding biological confirmation, such as PCR. (R.A.)