Cholangiocarcinoma is a biliary tumor, which not infrequently complicates primary sclerosing cholangitis. It carries a poor prognosis and, with the exception of carefully selected individuals in research protocols, contraindicates orthotopic liver transplantation. There has been some suggestion that cholangiocarcinomas incidentally discovered at the time of transplantation carry a better prognosis. The goal of this retrospective study was to perform a national review of outcomes after liver transplantation in Canadian recipients found to have incidental cholangiocarcinoma in their explanted native liver. Six of the seven liver transplant centers in Canada provided clinical and follow-up information on all liver transplant recipients found to have incidental cholangiocarcinoma in their explants. The diagnosis or suspicion of cholangiocarcinoma prior to transplantation were exclusion criteria for this study. Ten individuals with cholangiocarcinoma were transplanted between 1996 and 2003. The median duration of follow-up was 28 months. Eight of the 10 had PSC. All of the tumors were stage I or II. The 3-year survival for these patients was 30%. The median time to recurrence was 26 months (95% confidence interval 13 -37), and the median time to death was 30 months (95% confidence interval 28 -53). In conclusion, although early survival of patients transplanted for incidental cholangiocarcinoma appears good, intermediate-and long-term survival rates are not better than for individuals historically transplanted with known cholangiocarcinoma. Aggressive investigation for cholangiocarcinoma is mandated. Incidentally found tumours remain a difficult treatment problem, and prospective adjuvant chemo-, radio-, and immunotherapies should be investigated. (