We have examined the expression of c-myc and c-myc promoter binding protein (MBP-1), a novel eukaryotic repressor, in human hepatocellular carcinoma and cirrhosis by semiquantitative reverse transcription PCR amplification. Levels were normalized for glyceraldehyde-3-phosphate dehydrogenase messenger RNA and then compared between these two groups and to normal liver. We found that MBP-1 expression was significantly decreased in cirrhosis and c-myc and MBP-1 were even further diminished in hepatocellular carcinoma. There was no clear correlation between MBP-1 and c-myc messenger RNA levels. Our results therefore suggest that expression of MBP-1 and c-myc are decreased in a stepwise fashion in the presence of chronic liver disease and hepatocellular carcinoma in humans and that further study of the interactions of these two genes and their products is warranted to determine their role in human hepatocarcinogenesis.