Preneoplastic and neoplastic lesions in rodent liver show alterations in the expression of various enzymes which can be used for their identification. To address the question whether these enzymatic alterations result from specific changes in the levels of hepatocyte-enriched nuclear factors (HNF), we analysed the mRNA levels of six different HNFs (HNF-1alpha, beta, HNF-3alpha, beta, gamma, and HNF-4) by RNase protection assay in chemically induced liver tumours and corresponding normal liver tissue from mice of three different strains. When compared with the normal liver tissue, HNF-1beta, HNF-3alpha and HNF-3beta showed unchanged expression levels in the various liver tumours, which HNF-1alpha and HNF-4 mRNAs were lowered by 20-30%, and HNF-3gamma mRNA was increased by 50%. There were no significant differences in HNF-expression between tumours harbouring point mutations at codon 61 of the Ha-ras protooncogene and tumours without detectable Ha-ras mutations.