摘要:Introduction: Polymorphisms within miRNAs binding sites are associated with miRNAs function. The aim of this study was to investigate the relationship between rs61764370 polymorphism within let-7 miRNA binding site in KRAS gene and the risk of lung cancer in Iranian population. Methods: This case-control study was conducted with 100 lung cancer patients and 100 healthy persons. The rs61764370 polymorphism was analyzed using PCR-RFLP technique and direct sequencing. Results: We found a significant relationship between rs61764370 (T / G) polymorphism and lung cancer risk, the GT gen- otype (OR: 6.25; 95% CI = 2.605-15.00; P= 0.000) and G allele (OR: 5.25; 95% CI = 2.259–12.208; P= 0.000) were signifi- cantly associated with an increased risk of lung cancer. Conclusion: According to our findings, there is a significant relationship between the KRAS rs61764370 polymorphism and lung cancer risk in Iranian population and this polymorphism may be used as a marker in detection of lung cancer in the future.