Background/Aim. About 1.8 million new lung cancer cases are diagnosed in the world every year, and about 1.6 million cases are with fatal outcome. Despite improvements in treatment in previous decades, the survival of patients with lung cancer is still poor. The five-year survival rate is about 50% for patients with localized disease, 20% for patients with regionally advanced disease, 2% for patients with metastatic disease, and about 14% for all stages. The median survival of patients with untreated NSCLC in the advanced stage is four to five months and the annual survival rate is only 10%. The main goal of the research is to obtain and analyze the results of treatment with concomitant chemotherapy in terms of its efficacy and toxicity in selected patients with locally advanced inoperable non-small cell lung cancer. Methods. The study included data analysis of 31 patients of both sexes who were diagnosed and pathohistologically verified with NSCLC in inoperable stage III and were referred by the Council for Malignant Lung Diseases to the Radiotherapy Department of the Military Medical Academy for concomitant chemoradiotherapy treatment. Upon expiry of the three-month period from the performed radiation treatment, the tumor resonance was assessed on the basis of MSCT examination of the chest and upper abdomen according to RECIST 1.1 criteria (Response Evaluation Criteria in Solid Tumors). According to the same criteria, progression-free survival (PFS) was also assessed every three months during the first two years, then every 6 months or until the onset of disease symptoms, as well as overall survival (OS). Result. The median progression-free survival is 13 months, and the median overall survival is 20 months. During and immediately after RT, 9 (29%) patients had a grade 2 or higher adverse event. Conclusion. The use of concomitant chemoradiotherapy in patients in the third stage of locally advanced inoperable non-small cell lung cancer provides a good opportunity for a favorable therapeutic outcome, with an acceptable degree of acute and late toxicity, and represents the standard therapeutic approach for selected patients in this stage of the disease.