Lung cancer is the deadliest cancer in Iran after gastric cancer. The vast majority (85%) of cases of lung cancer are due to long-term tobacco smoking. About 10–15% of cases occur in people who have never smoked. These cases are often caused by a combination of genetic and environmental factors. Many human cancers are the result of mutations in the RAS family, and lung cancer is no exception. In this study, mutations in codon 12 and 13 of exon two were performed in 50 lung tumors from the Iranian Institute of Oncology. The exon 2 of the gene was amplified by PCR and sequenced for detection of the point mutation in codon 12 and 13. Of the 50 samples, 13 had mutations in codon 12 and 13, of which only two patients had single mutations in codon 12. No significant relationship was not found between age (P = 0.43) and gender (P = 0.37) and mutations in this gene. No significant relationship was found between disease stage and mutation in this gene (P = 0.51). Identifying k-ras gene mutations as an oncogene and having an effect on the treatment process can help the physician to choose the appropriate treatment.