Introduction. - Clostridium difficile is a spore-forming, anaerobic, Gram-positive bacillus responsible for 15% to 25% of cases of post-antibiotic diarrhea and more than 95% of cases of pseudomembranous colitis (PMC). This article summarizes the current understanding of C. difficile infections and recent developments in this field. News and highlights. - Since 2003, outbreaks of severe C. difficile diarrhea have been reported in Canada and the United States. These outbreaks are linked to the emergence and spread of a specific C. difficile clone known as 027, based on its PCR-ribotyping profile, or North American pulsotype 1 (NAP1), based on its pulsed-field gel electrophoresis profile. This clone is unique in that it produces larger quantities of toxins A and B in vitro and tests positive for a third toxin called binary toxin. This clone has spread to Great Britain, Belgium, the Netherlands, and more recently to France, where it has caused outbreaks, primarily in the Nord-Pas-de-Calais region. Outlook and plans. - Systematic surveillance of incidence. (R.A.)