PURPOSE. To investigate the sensitivity, specificity, and spatial distribution of the product of p28 gene (p28(GANK) protein) in human hepatocellular carcinoma (HCC) and nonhepatocellular carcinomas in relation to immunostaining with Cytokeratin 18 (CK18), alpha-fetoprotein (AFP), and Hepatocyte paraffin 1 (HepPar1). METHOD. In this retrospective study, formalin-fixed paraffin-embedded tissues from 24 HCCs, five intrahepatic cholangiocarcinomas (ICC), five combined hepatocellular cholangiocarcinomas (C-HCC-CC) and mine metastatic hepatic carcinomas (MHC) were immunostained for p28(GANK) as well as CK18, AFP and HepPar1. Only cases with more intensified staining in carcinoma contrast to the adjacent liver tissues were accepted as positive. RESULT. In HCC, p28(GANK) was expressed restrictively in hepatocytes of both para-lesion and carcinoma liver tissues, while absent in the bile duct epithelial cells, Kupffer cells, and other interstitial cells. The positive staining of p28(GANK) was noted in 16 (66.7％) specimens of HCC and three (60.0％) specimens of C-HCC-CC, and no specific lesion staining was found in all tested specimens of ICC and MHC. Sensitivity and specificity for hepatocyte-originated carcinoma were, respectively, 65.5％ and 100％ for p28(GANK), 79.3％ and 85.2％ for CK18, 20.7％ and 100％ for AFP, 79.3％ and 92.0％ for HepPar1. CONCLUSION. The hepatocytic staining for p28(GANK) is clearly useful in differentiating hepatocyte-originated carcinoma from non-HCC. p28(GANK) may be used as an ancillary marker for the diagnosis of HCC.