This is the first study evaluating expression profile of DNMT1, DNMT3A and DNMT3B genes in lung large cell neuroendocrine carcinoma patients. Large cell neuroendocrine carcinoma is a subtype of non-small-cell lung carcinoma with unknown methylation characteristics, including enzyme activities of DNA methyltransferases. We performed quantitative expression analyzes of DNMT1, DNMT3A and DNMT3B genes on formalin-fixed, paraffin-embedded tissue samples of lung large cell neuroendocrine carcinoma patients, and overexpression of DNMT1 and an increased normalized expression of both DNMT3A and DNMT3B genes relative to matched normal lung tissue were found. In conclusion, we assume that further experiments should be focused on the detection of individual DNMT3B isoforms in patients with this type of non-small cell lung carcinoma.