Abstract: Objective To explore the protection of prostaglandin E₁ injection with radiation-induced lung injury. Methods Thirty-nine female Sprague-Dawley rats were randomly divided into three groups:blank control group, radiation alone group and radiation plus drug group. Irridiation was given to the whole right lung by a single dose of 20Gy with 8MeV electon. Prostaglandin E₁ injection 10μg·kg^-1·d^-1 was injected into the rats of radiation plus drug group by vena candalis per day for five days, starting on the first day. Animal of each group were sacrificed on days 5, 15, 30 respectively after irradiation. Transforming growth factor-β₁ (TGF-β₁) level in serum was measured and sections of right lung tissues were observed by hematoxylin and eosin staining. Results Pulmonary edema and pneumonia aggravated gradually. TGF-β₁ increased significantly beginning from day 5, especially on days 15, 30 (P<0.05) in group radiation and radiation plus drug. TGF-β₁ decreased on days 15, 30 (P<0.05) in group radiation plus drug. Conclusions Prostaglandin E₁ injection could decrease serum TGF-β₁ content. Inhabiting expression of TGF-β₁ in the lung tissue might be one of the mechanisms in treatment of radiation lung injury.