The methylation profiles of nine cancer-associated genes were compared with the percent of methylation ratio (PMR) using quantitative methylation RT-PCR in 16 normal lung tissue samples and 80 non-small cell lung cancer (NSCLC) tissues samples. The methylation of nine cancer-associated genes showed a significant increase in tumors compared to matched normal lung tissues, and the level of gene methylation in NSCLC patients containing both adjacent non-tumor and tumor tissues showed a significant increase compared to normal lung tissues (P<0.05). The hypermethylation of the p16, RASSF1A, and CYP1B1 genes were correlated with age at diagnosis. APC, RASSF1A, and CYP1B1gene hypermethylation was correlated with smoking status according to a cut-off of PMR values of 10. TWIST1 gene hypermethylation was correlated with histologic types. Kaplan-Meier survival analysis using the methylation status of nine genes demonstrated that only p16 gene hypermethylation was associated with the survival period. Our results of this study provide evidence that hypermethylation of cancer-associated genes containing a tumor suppressor may serve as an early detection marker for lung cancer progression.