Background: Lung cancer is the leading cause of cancer death, late diagnosis being the main obstacle to improving the outcomes with stage at diagnosis as an important prognostic factor. Relationships between ABO blood groups and risk of benign or malignant diseases have been observed and in this study, we aimed to investigate whether they might affect prognosis and response to chemoradiotherapy in patients with local advanced non-small cell lung cancer (NSCLC). Materials and Methods: Eighty-one patients with non-metastatic local advanced NSCLC were included in the study. ABO blood groups were A in 45 (55.6%), B in 7 (8.6%), AB in 8 (9.9%), and O in 21 (25.9%) patients. The patients were also divided two groups according to blood group A (45 patients) and non-A (B, AB and O; 36 patients). Response to chemoradiotherapy was complete remission in 10 (12.3%), disease regression in 42 (51.9%), stable disease in 12 (14.8%), and disease progression in 17 (21.0%) patients. Results: There was no significant difference among ABO blood group categories or between patients with A blood group and those with non-A blood group in terms of responses to chemoradiotherapy (p>0.05). There were also no significant differences regarding overall and disease-free survival rates. Conclusion: The ABO blood group system has no significant effect on prognosis and response to chemoradiotherapy in patients with non-metastatic NSCLC.