Deletions of the Tg737 gene, whose product is involved in liver oval cell proliferation, differentiation, and ploidy control, have been recently shown in chemically induced rat liver tumors and in a limited series of patients with hepatocellular carcinoma (HCC). Thus, Tg737 has been proposed as a candidate new liver-specific tumor suppressor gene. To investigate this important issue, we analyzed the structure and expression pattern of the Tg737 gene in a group of 23 tumorous and adjacent nontumorous liver tissues, by combining polymerase chain reaction (PCR) and Southern and Northern blot–based analyses. We failed to identify deletions or gross alterations of the Tg737 gene by both PCR and Southern blot analyses. Northern blots showed comparable accumulation of normal Tg737 transcripts in both tumorous and nontumorous tissues. Collectively, therefore, our results do not support the hypothesis of frequent Tg737 genetic alterations in human HCC.