The aim of this study was to study the relationship of EGFR DNA methylation with the severity of non-small-cell lung cancer (NSCLC). We enrolled 54 patients with NSCLC between March 2013 and June 2014 from Department of Cardiothoracic Surgery in our hospital. The methylation levels in the promoter region of the EGFR gene in cancerous and pericarcinomatous tissue were tested by pyrosequencing. EGFR mRNA expression levels were detected by real-time reverse-transcription polymerase chain reaction. The SPSS software was used for data analysis.