PURPOSE: Clostridium difficile is an anaerobic gram positive, spore-forming bacterium which is responsible for 15-25% of antibiotic-associated diarrhea and for more than 95% of pseudomembranous colitis (PMC). This paper will review the main knowledge on C. difficile-associated infections and their recent evolution. CURRENT KNOWLEDGE AND KEY POINTS: Since 2003, outbreaks of severe C. difficile-associated diarrhea (CDAD) have been increasingly reported in Canada and the United States. This trend is assumed to be associated with the rapid emergence and spread of a specific clone of C. difficile belonging to PCR-ribotype 027 or North American Pulsotype 1, pulsotype (NAP1). This clone is characterized by the overproduction of toxins A and B and is positive for a third toxin named binary toxin. This clone has spread in UK, in Belgium, in the Netherlands, and, more recently, in France where it has been responsible for large outbreaks mainly in northern France. FUTURE PROSPECTS AND PROJECTS: A systematic reporting of C. difficile incidence by health facilities should enable a better assessment of this pathology in France.