PURPOSE:Clostridium difficile-associated diarrhea (CDAD) is a potentially life-threatening illness which has been shown to be more common and more severe in patient with chronic renal failure. The aim of this study was to investigate clinical characteristics of renal insufficiency patients with clostridium difficile-associated pseudomembranous colitis. METHODS:We reviewed charts of fifty-six patients with clostridium difficile-associated pseudomembranous colitis, who have clostridial toxin A assay in stool and a diagnosis made on histology of colonic biopsies. RESULTS:There was no difference in age, serum albumin, C-reactive protein (CRP) and negative incidence of clostridial toxin A between patients who had renal insufficiency with serum creatinine more than 1.5 mg/dL and those who did not. But duration of antibiotic use administered prior to development of the clostridium difficile infection was more shorter in patients with impaired renal function than in patients with normal renal function. CONCLUSION:These data suggest that it may take a short period to development of the clostridium difficile infection in patients with impaired renal function, and histologic evaluation by sigmoidoscopy should be performed to make a diagnosis in CDAD-suggested patients, who have impaired renal function and even negative clostridial toxin A.