Introduction - This article reviews the seasonal influenza surveillance conducted by the Military Influenza Surveillance System (Smog), which was integrated into the Regional Influenza Surveillance Groups (Grog) over the past four seasons, from 2004 to 2008. Method - Smog consists of 30 sentinel units that submit weekly epidemiological data identical to that collected by the Grog network, as well as samples taken from individuals suspected of having influenza. Results - According to Smog data, the last three influenza epidemics were moderate, unlike the 2004–2005 epidemic, which was more severe. Virological data reported 133 influenza viruses isolated over the four seasons. Virus A accounted for 86% of influenza cases in 2004–2005 and 92% in 2006–2007. During the 2005–2006 season, virus B was the predominant circulating virus (72% of samples). The 2007–2008 season was characterized by the co-circulation of influenza A (55%) and B (45%) viruses. Conclusion—The Smog data were consistent with those from the Grog. Smog appears to be very well integrated into the national surveillance system. (R.A.)