The occurrence of de novo hepatocellular carcinoma after liver transplantation is a rare event with only few cases reported in the literature. In a post liver transplantation setting distinguishing between a de novo hepatocellular carcinoma from recurrence should be tested with molecular analysis such as fluorescent in situ hybridization (for sex chromosomes) or microsatellite analysis. Nevertheless, a certain degree of epithelial chimerism between recipient and donor tissues could be responsible for the development of de novo hepatocellular carcinoma of recipient origin. We report two cases of de novo hepatocellular carcinoma after liver transplantation. The first one occurred in a patient receiving transplantation for hepatitis C related cirrhosis and hepatocellular carcinoma. A de novo hepatocellular carcinoma developed five years after transplantation and microsatellite analysis revealed the donor origin of the neoplasia. The second one occurred in a patient who received transplantation for secondary sclerosing cholangitis. Hepatocellular carcinoma was found six years after transplantation. Both microsatellite analysis and fluorescent in situ hybridization revealed the recipient origin of the tumor, potentially due to tissue chimerism.