To further investigate the possible usefulness of antitransferrin receptor staining in the differential diagnosis between benign and malignant primary liver tumours, we examined the transferrin receptor expression in ten cases of focal nodular hyperplasia, six of nodular regenerative hyperplasia, two adenomas and six hepatoblastomas. In focal nodular hyperplasia, the ductular structures were always positive and the parenchymal cells displayed three staining patterns of moderate intensity. In nodular regenerative hyperplasia there was scattered, relatively weak transferrin receptor staining. The tumour cells in the adenomas were only weakly positive. Three hepatoblastomas showed an intense staining of tumour cells; one was weakly positive and two were negative. A high intensity of transferrin receptor staining, as previously described in hepatocellular carcinomas, was only observed in the hepatoblastomas. This gives further credence to the usefulness of strong transferrin receptor expression in evaluating the malignant nature of tumour foci in liver biopsies.