The aim of this study is to assess whether the celecoxib has a radioprotective effect in the rat model of radiation-induced lung injury. Rats were given a single dose of 20 Gy to the right hemithorax and mediasten region from 80 cm distance and I cm depth by a (60)Co teletherapy unit. Histopathological evaluation was fulfilled using light microscope and the biochemical results were evaluated by considering membrane lipid peroxidation. Biochemical and histopathological results of 20 Gy irradiated lungs revealed significant tissue damage. In only radiation applied group (Group-3); macrophage clusters in alveolar structures, diffuse alveolar septum thickness, bronchial lymphocytes in groups and diffuse peribronchial edema were determined (radiation pneumonitis). It was seen that plasma MDA level was fairly elevated in irradiated lungs. But four dose of celecoxib precluded the radiotherapy induced lung damage significantly when compared to the control group (p < 0.05). It was thought that two dose of celecoxib alleviated the radiotherapy dependent lung damage. Biochemical and pathological evaluation of the animals in Group-4 showed that four dose of celecoxib lowered the radiotherapy induced lung damage significantly. In only celecoxib applied group (Group-5), biochemical and pathological results showed that celecoxib didn't cause any change in normal lung tissue.