In France, since 1988, anonymous and free HIV testing centers (CDAG) have been established in every department to enable individuals to voluntarily undergo HIV testing. There are currently more than 380 CDAGs, whose mandates have been regularly expanded by health authorities. They are tasked with promoting early testing, facilitating access to testing for people in precarious situations and those at risk, and strengthening prevention by helping clients develop a personal prevention strategy for HIV, as well as HCV, syphilis, and other sexually transmitted infections. They must also strengthen the link between testing and care. CDAGs serve a young population, which is therefore at higher risk for HIV infection than the general population. Their activity is steadily increasing, and their positive screening rate is double that of medical testing laboratories. Between 1,000 and 2,000 positive HIV diagnoses are made in CDAGs each year, which accounted for 11% of positive serology results nationwide in 2002. Knowledge of the actual impact of CDAGs on HIV prevention and their role in screening is limited by anonymity and the intentionally limited scope of data collection. To better understand the profile of patients seeking care, data collection on clinic activity will be revised starting in 2004 and will be supplemented by a cross-sectional epidemiological survey and the establishment of a network of CDAGs to ensure more comprehensive and continuous collection of epidemiological data.