A 55-yr-old woman presented to the emergency department at a general hospital in Japan with a 3-day history of fever and upper back pain.She was diagnosed with metastatic pancreatic cancer and underwent systemic chemotherapy with a modified FOLFIRINOX regimen (oxaliplatin 65 mg/m2, leucovorin 200 mg/m2, irinotecan 150 mg/m2, fluorouracil 400 mg/m2 given as a bolus followed by 2400 mg/m2 given as a 46-h continuous infusion).She had received the third cycle of chemotherapy 12 days before her visit to the hospital and a single dose of PEG-G-CSF 7 days before her visit to hospital.Her blood test showed her leukocyte count was 15 600 cells/μL and her C-reactive protein level was 11·0 mg/dL.On the following day of her stay in hospital, contrast CT scan revealed contrast-enhanced wall thickening of the aortic arch and descending aorta (figure).Thus, the diagnosis of G-CSF-associated aortitis was made, and treatment with 60 mg of i.v. methylprednisolone (1·0 mg/kg/day) was initiated.The methylprednisolone dose was successfully tapered to 40 mg per day on the 11th day of her stay in hospital without any flare-up of her symptoms.In conclusion, it is essential to consider the possibility of G-CSF-associated aortitis in patients on chemotherapy.Systemic glucocorticoid therapy is an option in the management of G-CSF-associated aortitis, but the treatment plan should be individualized according to the patient's condition.