Background: Granulocyte colony-stimulating factor (G-CSF) is widely used to treat chemo- or radiotherapy-induced neutro-penia and is also effective in the treatment of severe oral mu-cositis induced by chemotherapy. With the common use of G-CSF the description of rare or new side effects becomes more important. Case Report: The 44-year-old male patient suffered from an inoperable carcinoma of the nasopharynx and underwent a combined radio-chemotherapy, consisting of paclitaxel weekly and irradiation with 70 Gy over 7 weeks. During the course of treatment, he developed a severe oral mucositis. Since conventional therapy of mucositis did not alleviate the symptoms, he was treated with G-CSF. Within 18 h after the subcutaneous administration of G-CSF he developed a severe facial angioedema. Within 3 days the patient recovered spontaneously from the angioedema. Because the relationship of the symptoms and the G-CSF treatment was not clearly evident, a second dose of G-CSF was given. 14 h after the subcutaneous injection of the same dose of G-CSF, the patient developed the identical symptoms of angioedema. Conclusion: Facial angioedema is a rare but important side effect after G-CSF treatment. A possible role of paclitaxel or radiation therapy in the pathogenesis of this side effect cannot be ruled out.