Risk factors for Clostridium difficile diarrhea are antibiotic exposure, hospitalization, extreme ages, and immunodeficiency. Patients with CF have a high rate of colonization with C. difficile. We performed a retrospective chart review of patients at Texas Children's Hospital who underwent lung transplantation since the inception of our program in October 2002 until October 2008. There were 78 pediatric lung transplants performed at our institution during the study period. Four patients developed six total episodes of CDC for an overall incidence of 5.4%. CF was the underlying diagnosis in all four patients, leading to an incidence of 8.9% in patients with CF. Two patients developed colitis within the first four months following transplant, and the other two patients developed colitis more than three yr after transplantation. All four patients required hospitalization, and three patients were managed medically while one patient underwent diverting ileostomy. One experienced renal insufficiency and subsequently expired. Overall survival was 75% among patients with CDC following lung transplantation. CDC causes significant morbidity and mortality in children with CF who have undergone lung transplantation.