This article presents an epidemiological, clinical, and virological overview of influenza activity in mainland France during the 2011–2012 season. Methods. This overview is based on a descriptive analysis of influenza surveillance data provided by outpatient medical networks, virological analyses from partner laboratories, reports of outbreaks of acute respiratory infections (ARI) in elderly care facilities, surveillance of emergency department visits and hospitalizations for influenza, surveillance of severe influenza cases hospitalized in intensive care units, and analysis of available mortality data in metropolitan France. Results. In metropolitan France, the 2011–2012 season was characterized in the community by a moderate-intensity influenza epidemic that occurred late, between late January and late March 2012. Virological surveillance showed that influenza A(H3N2) viruses were the predominant circulating strains, a significant proportion of which were antigenically different from the vaccine strain. Numerous outbreaks of acute respiratory infections (ARIs) in elderly care facilities were reported to the French Institute for Public Health Surveillance. Hospitalization rates were higher among people aged 65 and older than in the previous year. The majority of severe cases admitted to intensive care involved people aged 65 and older infected with the A(H3N2) virus; these epidemiological characteristics differed from those of the two previous seasons. An excess of all-cause mortality was observed among people aged 85 and older, compared with data from previous years for the same period. Conclusion. The predominant circulation of the A(H3N2) virus in mainland France, accompanied by a significant proportion of antigenic variants, likely contributed to a more pronounced influenza epidemic among people aged 65 and older. (R.A.)