Abstract: Objective This study designed to assess a quantitative molecular assay of serum DNA and the expression of hTERT in patients with lung cancers to explore a novel noninvasive approach,elevating the sensitivity and specificity in diagnose of lung cancer. We conducted the clinical study to provide a new marker for earlier lung cancer detection. Methods Forty-one informed patients with lung cancers and 22 healthy persons were included as control. DNA was extracted from serum samples with MaGaZorb DNA Mini-Prep Kit and quantificated, then hTERT sequences was amplified by nested PCR using gene primers. Results 　Mean concent ration of serum DNA between patient s with lung cancers and healthy persons was 33. 464μg/ ml and 18. 420μg/ ml respectively. Concent ration of f ree circulation DNA in patient s with lung cancers was higher than the other group ( P < 0. 01) . The area under the ROC curve by ratio of gray scale was 0. 852 (95 % CI, 0. 750 to 0. 953) . Amplification of serum hTERT by nested PCR was a approach with moderate veracity to detect lung cancers. Meanwhile, it had a good coherence with pathology ( Kappa = 0. 477, P < 0. 01) . Conclusion 　The level of f ree circulating DNA in patient s with lung cancers was higher than healthy persons. Amplification of serum hTERT by nested PCR was a approach with high sensitivity. So it may be a new, noninvasive approach for early detection of lung cancers.