In the current study, we genotyped 35 single-nucleotide polymorphisms (SNPs) in 7 MMR genes (MLH1, MSH2, MSH3, MSH4, MSH5, SAPCD1 and MSH6) in lung cancer patients, and evaluate the relationships between these genetic polymorphisms and platinum-based chemotherapy prognosis. The gene discussed is MSH5; the disease is lung carcinoma.