Clostridium difficile has been implicated as one cause of hospital-acquired diarrhea in children, yet the prevalence of this organism in outpatient children with diarrhea has not been established. Over a 1-year period, 306 outpatient children ranging in age from 2 weeks to 16 years were cultured for C. difficile and potential bacterial pathogens. C. difficile was isolated from 7.0% of patients with diarrhea (12 of 171) and 14.8% of controls with nondiarrheal illnesses (20 of 135). The 32 patients yielding C. difficile were significantly younger than the other study patients. C. difficile was isolated in conjunction with another enteric pathogen in only one case. Antibiotic exposure in the month prior to culture was no different between the 32 positive patients and the overall population. Moreover the patients yielding C. difficile were clinically indistinguishable from the other study patients. C. difficile appears to comprise part of the normal bowel flora in some children beyond the neonatal period and despite a negative history of recent antibiotic usage.