['Promoter methylation is an alternative mechanism of gene silencing in human tumorigenesis. Although a number of methylated genes have been found in non small cell lung cancer (NSCLC), useful methylation markers for early prognostic evaluation of NSCLC remain largely unknown.', 'Using methylation-specific PCR (MSP), we examined promoter methylation status of PAX6 gene, and explored their association with clinical features in NSCLC via chi-square test. NSCLC patient survival was assessed by Kaplan-Meier analyses and a Cox proportional hazard model was employed for multivariate analyses.', 'The methylation level of PAX6 gene was higher in tumor tissues than that in normal tissues. In addition, PAX6 promoter methylation showed a very significant correlation with differentiation (P = 0.002), distant metastasis (P = 0.024), and TNM stage (P = 0.002). PAX6 gene promoter hyper-methylation was found to be significantly associated with poor overall survival (P = 0.018) and to serve as an independent marker for prognosis using multivariate Cox regression analysis (HR: 2.254, 95% CI: 1.088-4.667, P = 0.029).'] Is down-regulation of PAX6 by promoter methylation associated with poor prognosis in non small cell lung cancer?