Clostridium difficile is the main cause of nosocomial gastrointestinal disorders. Historically, C. difficile has usually affected older patients, hospital inpatients, and long-term care facility residents. Recent reports suggest that the occurrence and severity of C. difficile-associated disease (CDAD) is increasing in populations previously considered to be at low risk of the infection, and increasing numbers of community-acquired cases of CDAD are being reported. Risk factors for CDAD in paediatric patients include disruption of the normal microflora of the gastrointestinal tract (antibiotic-associated and non-antibiotic-associated), age, immune status, diet, underlying conditions, concurrent infections, and cancer. CDAD in populations previously thought to be at low risk is an emerging problem.