Abstract: Objective : To study the clinical significance of telomerase activity and human telomerase reverse transcriptase (hTERT) mRNA expression for differential diagnosis of malignant and benign liver lesions. Methods : Telomerase activity was detected by ELISA-TRAP assay in 130 surgical resected liver samples and 58 percutaneous biopsied liver samples. Expression of hTERT mRNA was also measured by RT-PCR assay in these samples. Postoperative pathological examination was performed for every case. Results : Among the 130 surgical liver samples, the positive rates of telomerase activity in hepatocellular carcinoma (HCC), liver cirrhosis, chronic hepatitis tissues were 85.9%(55/64), 25.0%(8/32) and 8.3%(2/24) respectively, and the positive rates of hTERT mRNA expression were 89.1%(57/64), 25.0%(8/32) and 8.3W(2/24) respectively. Neither telomerase activity nor hTERT mRNA expression was detected in 10 normal liver tissues. Among the 58 biopsied liver specimens, the positive rates of telomerase activity in HCC, cholangiocellular carcinoma, focal nodular hyperplasia, inflammatory pseudotumor and adenomatous hyperplasia tissues were 85.7%(30/35), 100%(4/4), 33.3%(4/12), 25.0W(1/4) and 33.3W(1/3) respectively, and the positive rates of hTERT m R N A expression were 88.6%(31/35), 100% (4/4), 33.3% (4/12), 25.0) (1/4) and 33.3% (1/3) respectively. The positivity of telomerase activity or hTERT mRNA expression in malignant liver tumors was significantly higher than that of in benign liver lesions (P<0.01). conclusion : Detection of telomerase activity or hTERT mRNA expression in percutaneous biopsied liver tissues may be useful for differential diagnosis of malignant and benign liver lesions.