In 2001, health authorities made it mandatory to report certain rare or serious nosocomial infections in order to detect them early and facilitate their investigation and control. In 2006, 1,007 reports totaling 3,239 infections were received from 431 healthcare facilities; 304 of these reports involved clusters of cases. Reporting rates and response times varied by facility type and region. The most frequently reported microorganisms were Clostridium difficile (19% of reports), Staphylococcus aureus (11% of reports), Enterobacteriaceae (9%), and Pseudomonas aeruginosa (8%). In 2006, the reporting system enabled the detection of the emergence of C. difficile infections of type 027 and provided support to healthcare facilities in implementing control measures. The system’s ability to rapidly detect and control outbreaks remains dependent on professional adherence, a link to structured microbiological expertise, and the responsiveness of coordination and expertise structures. (R.A.)