To investigate the current status of radiotherapy (RT) trends in the definitive treatment of lung cancer in Turkey. A questionnaire consisting of 46 questions about the technical facilities, and indications regarding the definitive radiotherapy of lung cancer was sent to 62 centers in Turkey, and was answered by 47 centers. RT centers were mostly gathered in Marmara, Central Anatolia, and Aegean region (15, 12 and 8 centers respectively). The median number of patients with non-small cell (NSCLC) and small-cell lung cancer (SCLC) treated definitively in one year were 55 and 15 respectively. The cases are discussed in a multidisciplinary tumor board in 75% of the centers. All of the centers use at least the minimum technological standard which is CT-planned 3D conformal RT (3D-CRT) in the definitive treatment of lung cancer; 33% has 4D-CT simulation facility, 94% use PET/CT in RT planning, 75% apply RT under image guidance; 41% has stereotactic body radiotherapy (SBRT) facility, and 53% use SBRT routinely in early-stage NSCLC patients who are medically inoperable or who refuse surgery. Ninety-eight percent of the centers apply concurrent chemoRT (87% starting RT with the first chemotherapy course) in locally advanced NSCLC. Concurrent chemoRT dose is 60-66 Gy in 96%. Chemotherapy was given by the radiation oncologists in 34% of the centers. In stage IIIA (N2) potentially resectable disease 56% of the centers apply neoadjuvant treatment (chemoRT 67%, chemo 33%). Besides main postoperative RT indications 27% of the centers apply RT to patients with inadequate mediastinal dissection, 37% apply to patients with suboptimal surgery. Regarding definitive treatment of SCLC 17% of the centers apply 45 Gy bid, 50% apply 50-60 Gy, 28% apply 61-66 Gy concurrent with cisplatin-etoposide, starting with the first or second course in 87%. In extensive-stage SCLC 89% of the centers apply thoracic RT (50-66 Gy in 62%, 30 Gy in 26%) after chemotherapy. Prophylactic cranial irradiation doses were 25 Gy in 71%, 30 Gy in 22%. The patients are followed with 3-month intervals in 89% of the centers, however there is no consensus regarding follow-up workup among the centers. At least minimum world standards can be applied in the definitive RT of lung cancer in Turkey. The problems regarding optimal RT dose and fractionation and concurrent chemotherapy regimen, postoperative RT indications are similar, but as a developing country we need more multidisciplinary workup and develop our own guidelines taking into account our own resources and patient characteristics.