In a previously healthy 12-week-old male infant with a two-week history of poor feeding, colic, and bloody stools, pseudomembranous colitis developed. No prior antibiotics were administered although the child had received dicyclomine hydrochloride. Clostridium difficile and its toxin were detected in the child's stool. Severe disseminated intravascular coagulopathy developed; the patient required total colectomy but eventually recovered. Clostridium difficile colonization has not, to our knowledge, been previously documented in infantile pseudomembranous colitis.