Abstract: Objectives: To investigate the relationship between telomerase activity and p16 gene and its function in occurrence of lung cancer. Methods: Forty-eight lung cancer tissues, 7 normal lung tissues and 12 lung tissues adjacent to tumor were collected. The telomerase activity was detected using Telomerase PCR ELIAS Kit. The p16 gene transcription was detected by RT-PCR. The P16 protein was detected by immunohistochemistry analysis. Results: 1) The expression of telomerase activity were detected in 36 of the 48 (75.00%) lung cancer tissues and in 1 of the tissues adjacent to tumor. 2) The p16 gene mRNA transcription was expressed in 16 of 32 (50.00%) NSCLC tissues and in all the normal lung tissues. The p16 protein expression was not found out in 17 of 32 (53.13%) NSCLC tissues, but it can be detected in all normal lung tissues. 3) The p16 mRNA transcription can't be detected in 15 of 24 (62.50%) tissues, which showed the expression of telomerase. In one tissue the p16 mRNA was negative, but its telomerase was negative too (r=-0.433, P=0.013). Conclusions: Telomerase and p16 gene play an important role in oncogenesis. Telomerase activity will become a good marker in forecasting tumor's occurrence, diagnosing of cancer. Telomere, telomerase and p16 gene probably becomes a new target of anti-tumor therapy.