The purpose of this study was to elucidate the protein kinase C (PKC) alpha distribution in human hepatocellular carcinoma (HCC). The histoimmunopathologic technique was used to determine the localization and expression of PKCalpha in HCC biopsies. The HCC tissues were classified as cytosolic type (PKCalpha deposited in the cytoplasm in > 50% of cells) and membranous type for the remaining ones. There was a significant association of the membranous type with non-hepatitis C virus (HCV) infected patients. Moreover, the expression of PKCalpha in this type was significantly higher in HCC cells than that in the adjacent non-tumor liver cells. The result indicated that PKCalpha may play an important role in carcinogenesis of HCC patients with HBV infection and/or non-HCV infection.