The purpose of this study was to elucidate the function of protein kinase C (PKC) alpha in human hepatocellular carcinoma (HCC). Histoimmunopathologic techniques were used to determine the localization and/or expression of PKCalpha, phospho-mitogen-acrivated protein kinase (MEK) and multidrug resistance 1 (MDR1) in HCC biopsies. Expression of PKCalpha, phospho-MEK and MDR1 was significantly increased in the region of HCC location compared with the non-tumor location. The HCC tissues were classified as cytosolic type, where PKCalpha was deposited in the cytoplasm in > 50% of cells, or membranous type for others. The results showed that the higher expression levels of phospho-MEK and MDR1 in HCC location were significantly associated with those patients whose cells were of the membranous type. Moreover, the expression of MDR1 in HCC location was also significantly associated with the phospho-MEK, and was significantly higher in the patients with anti-HCV negative readings. The results indicate that elevated expression of MDR1 in HCC patients with non-HCV infection may be mediated through PKC signaling pathway.