Objective To analyze the value of 18F-fluorodeoxyglucose (FDG) posotron emission tomography/computed tomography (PET/CT) in the detection of relapsing polychondritis (RP) in fever of unknown origin (FUO) patients.Methods Retrospective analysis of the clinical data of 3 patients with FUO,who were final clinical diagnosed as RP,were conducted.Clinical symptoms,laboratory tests and 18F-FDG PET/CT image data were analyzed,and literature were reviewed.Results Three patients with FUO,2 had increased FDG uptake in PET/CT in multiple cartilages,including ear,nose,trachea/bronchial and rib cartilage (SUVmax 2.5-7.5),which were consistent with RP.One case with a history of RP,PET/CT detected pulmonary infla rrmatory lesions which might be the cause of fever.At the same time,PET/CT showed RP presentation in CT with nasal and airway structure changes,but there was no abnormal FDG uptake.Conclusion 18F-FDG PET/CT has an important clinical value in diagnosis and differential diagnosis of RP,and also in follow-up and clinical response observation.