&NA;Pruritus ani is a common condition in which there is a tendency for liquids to leak from the anal canal, resulting in perianal soiling. In order to ascertain if an abnormal fecal flora contributes to the irritant effects of fecal material, qualitative and quantitative measurement of the fecal microflora was performed in 20 patients with pruritus ani and 20 matched controls. No differences were found between the two groups. This study has failed to provide evidence for a microbiologic basis for pruritus ani.