Organizing pneumonia (OP) and eosinophilic pneumonia (EP) are known as lung injuries after radiation therapy for breast cancer. In this study, we reported nine cases of OP and a case of EP after radiation therapy. All 10 women (62±10 years of age) were nonsmokers. Nine patients received endocrine therapy after radiation therapy. The mean intervals from completion of radiation therapy to occurrence of any symptoms were 119 days. All the patients have symptoms, but none are severe. Seven patients were treated with corticosteroids, and three were without treatment. All patients improved, but a relapse occurred in three (two treated with corticosteroid, one without treatment). Because of our findings and the previous studies, tobacco smoke may have played a suppressive role in the occurrence of lung injury in nonirradiated areas after radiation therapy in breast cancer patients, and endocrine therapy may have played a promotive role.