Since 2001, the mandatory reporting of certain rare or severe nosocomial infections (NI) has been required in healthcare facilities (HF), and the effective functioning of this reporting system depends in large part on the cooperation of hospital staff. From 2007 to 2009, 3,721 reports totaling 15,192 cases of infections or colonizations were received nationwide, representing an average of 1,240 reports per year, a 23% increase compared to 2006; 35% of the reported cases were cluster cases. The microorganisms most frequently cited in reports were Clostridium difficile (15%), Enterococcus spp. (14%), and Staphylococcus spp. (9%). In addition to providing daily support to healthcare facilities, the reporting system helped confirm the gradual containment of known regional outbreaks, particularly those involving C. difficile in the Nord-Pas-de-Calais region or glycopeptide-resistant enterococci in Lorraine. It also helped identify new emerging risks, such as those linked to the importation of highly resistant bacteria from abroad, or to certain outpatient care practices. In 2009, 46% of French healthcare facilities had submitted at least one report since 2001; disparities persisted in reporting rates across regions, partly due to certain regional outbreaks and reflecting varying levels of adoption of the system. New initiatives will soon strengthen this alert system: improved feedback mechanisms, updated training programs, and the rollout of the Sin@pse electronic reporting tool in late 2011. (R.A.)