In France, surveillance of invasive meningococcal disease (IMD) is regularly evaluated, and the results are used to adjust the observed incidence rates. Three surveillance data sources were compared: mandatory reporting (MR), the National Meningococcal Reference Center (CNR), and the Epibac network of hospital bacteriology laboratories. Cases meeting the adopted definition were matched by age, date of illness, and department. After examining dependencies between sources, the number of cases not reported in any source was estimated by selecting the log-linear model that best represented the data. To ensure the completeness of Epibac, we restricted the analysis to cases admitted to hospitals whose laboratories participated in Epibac in 2000. In 2000, 585 cases of IIM were reported, and 638 were estimated (95% CI: 602 to 673). Correlations between CNR and DO and between CNR and Epibac were identified. There was regional heterogeneity in capture rates for both DO and CNR. The completeness of the DO was 73% (95% CI: 69–77) and that of the CNR was 74% (95% CI: 70–78). Coverage within the Epibac network was estimated at 74% (95% CI: 70–78). The completeness of the DO in 2000 has increased compared to that of 1996. Given that this is a serious disease requiring the implementation of preventive measures among contacts of a case, a completeness of the DO close to 100% must be considered. (R.A.)