This report summarizes the surveillance of HIV/AIDS and sexually transmitted infections (STIs) conducted between 1996 and 2005 by the National Public Health Network (RNSP) and subsequently by the French Institute for Public Health Surveillance (InVS). The use of potent antiretroviral drug regimens, beginning in 1996, completely revolutionized the management and prognosis of people infected with HIV, resulting in a dramatic decline in AIDS cases and deaths. These ten years of surveillance were also marked by other major developments: an increase in risky sexual practices among gay men, the resurgence of STIs, a rise in the proportion of people of African descent among those infected, and the prevalence of co-infection with hepatitis viruses. At the same time, the number of drug users newly infected with HIV has decreased, thanks to their adherence to harm reduction policies. In response to these significant challenges, new surveillance tools have been implemented (mandatory HIV reporting coupled with virological surveillance, STI surveillance), population-based approaches have been developed, particularly among drug users and men who have sex with men, and surveys have been conducted to better track trends (study on co-infection and survey on Anonymous and Free Testing Clinics—CDAG). (R.A.)