Radiation-induced lung injury (RILI) is one of the most important complications in thoracic tumors. After gastric radiotherapy left lung can be negatively affected in a variable severity depending on several factors due to the close anatomic location. In this study, radiotherapy planning computerized tomography data of 35 gastric cancer patients were evaluated retrospectively in terms of radiationinduced lung injury radiologically. Our aim is to investigate the correlation between the dosimetric data and radiologic changes of the left lung in the treatment field with computerized tomography images in 3-6 months after RT. Median values of treatment volumes, for left lung V25, mean (D mean) and maximum (D max) doses were evaluated via dose-volume histogram. Factors that may contribute to damage such as age, concomitant chemotherapy, radiotherapy technique, surgery and tumor location were also analyzed. RILI was detected in 51.4% of patients. These were parenchymal changes in 71.2%, a decrease in lung volume in 22.8%, pleural changes in 22.7%. RILI development was significantly higher in patients undergoing boost (p< 0.05).