This study represents the first effort to evaluate the expression of DNMT1, DNMT3A, and DNMT3B genes in patients with LCNEC.<h4>Materials and methods</h4>We performed quantitative expression analyses of DNMT1, DNMT3A, and DNMT3B on formalin-fixed, paraffin-embedded tissue samples obtained from LCNEC patients. The gene discussed is DNMT1; the disease is large cell neuroendocrine carcinoma.