CMV colitis in an immunocompetent host is a rare occurrence. We report a case of CMV colitis after biliopancreatic diversion surgery. The diagnosis of primary CMV infection with CMV colitis was based on histological examination of tissues biopsies obtained at colonoscopy, serology positive for CMV-IgM and CMV-IgG antibodies and a good response to systemic gancyclovir treatment. Malnutrition and colonic mucosal damage, both consequences of biliopancreatic diversion surgery, were thought to be predisposing factors. To our knowledge this is the first report in the English language literature of an association between CMV colitis and status following biliopancreatic diversion surgery.