Introduction - AIDS surveillance in France relies on mandatory reporting (MR), the completeness of which had not been assessed since the early 1990s. The objective of this study is to provide a new estimate of the total number of AIDS cases in France and to assess the completeness of the databases used. Methods - The two-source capture-recapture method was applied to AIDS cases diagnosed between 2004 and 2006. The first source is the national mandatory reporting (MR) database for AIDS. The second source consists of two databases: the French hospital database on HIV infection (FHDH-ANRS-CO4), which does not include Aquitaine, and the database of the Aquitaine Clinical AIDS Epidemiology Group (GECSA-ANRS-CO3). Comparing the mandatory AIDS reporting database (n=3,816) with the combined FHDH and GECSA databases (n=3,328) identified the overlapping cases (n=2,204). Results - The completeness rate of the AIDS DO in France was estimated at 66.1% (95% CI [65.1–67.2]), that of the FHDH at 55.6% (95% CI [54.7–56.5]), and that of the GECSA for the Aquitaine region at 90.3% (95% CI [86.4–94.5]). The total number of AIDS cases diagnosed in adults aged 18 and older between 2004 and 2006 was estimated at 5,770 (95% CI [5,679–5,861]). Conclusion—Compared with the study conducted during the 1990–1993 period, the coverage of the FHDH increased from 47.6% to 55.6%, while that of the AIDS surveillance system decreased from 83.6% to 66.1%, a decrease likely linked to the implementation of the HIV surveillance system in 2003. (R.A.)