Telomeres are important for the function and stability of eukaryotic chromosomes. Telomeric DNA is shortened every time liver cells divide. Normal human liver cells have a limited proliferative capacity, but immortalized cells prevent the shortening of the end of chromosomes by the expression of telomerase, the enzyme that elongates telomeric DNA. Although many genetic alterations have been reported in hepatocellular carcinoma, whether all hepatocellular carcinoma are immortalized cells is not known. Therefore, the telomerase activity was analyzed in 38 frozen samples from human hepatocellular carcinoma by fluorescence-based TRAP Method. Telomerase activity was detected in 34 (89.47%) of 38 hepatocellular carcinoma tissues regardless of tumor size, but telomerase activity was detected in only 12 (31.58%) of 38 nontumor liver tissues from patients with hepatocellular carcinoma. Diagnosis of hepatocellular carcinoma is sometimes difficult when the hepatomas an small and are of the differentiated type. Our results showed that the expression of telomerase may be of great value in diagnosing hepatocellular carcinoma.