This article presents an epidemiological, clinical, and virological overview of influenza activity in France during the 2012–2013 season. Methods: This review 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: The 2012–2013 season in mainland France was characterized by a more intense community-based influenza epidemic than those of the three previous seasons, lasting 13 weeks—the longest among the 29 seasonal epidemics monitored since 1984. The epidemic began in late December and peaked two months later, exceeding the peak of the 2009 pandemic and subsequent seasons. Influenza viruses A(H1N1)pdm09, A(H3N2), and type B circulated, with type A viruses initially dominant, a trend that reversed in favor of type B viruses by late January. The number of outbreaks of acute respiratory infections in long-term care facilities remained lower than in 2011–2012. The number of flu-related visits to emergency departments increased compared to the two previous flu seasons. Among these patients, 6.8% were hospitalized, a proportion significantly lower than that of the previous season (8.2%). In total, 818 severe cases were admitted to intensive care, a number higher than in the previous season but lower than the 1,305 severe cases during the pandemic. These severe cases, younger than last year, were mainly infected with the A(H1N1)pdm09 virus. The case fatality rate for severe cases remained comparable to that observed during the three previous seasons. Conclusion: The 2012–2013 influenza epidemic was particularly long, marked by the co-circulation of three influenza viruses. Consequently, even though the severity of influenza this year was comparable to that of previous seasons, the impact of the epidemic in terms of visits for influenza-like illness and hospitalizations was greater. (R.A.)