The aim of this study was to estimate the correlation between telomerase activity and the expression of human telomerase RNA component (hTERC), human telomerase reverse transcriptase (hTERT) in patients with hepatocellular carcinoma (HCC), and to analyze the influence of the nucleotide homology of the hTERC template region on telomerase activity. Six HCC patients and two chronic hepatitis patients were enrolled in this study. Telomerase activity was determined using the fluorescence-based telomeric repeat amplification protocol (TRAP) method. Quantification of hTERC and hTERTmRNA was performed using a real-time PCR method. Furthermore, a portion of the hTERC gene was amplified using nested RT-PCR methods. After sub-cloning, the nucleotide sequence of the cloned hTERC that contained the template region was determined. Telomerase activity and hTERTmRNA was detected in all cancerous tissues, while hTERC was present in both tumorous and non-tumorous lesions. The level of telomerase activity correlated with expression of hTERTmRNA, but not that of hTERC. The nucleotide sequence of cloned hTERC was similar in both tumorous and non-tumorous lesions. The expression of hTERT may be a definitive factor in the activation of telomerase in hepatocarcinogenesis.