ObjectiveTo investigate the diagnostic value of 18F-FDG PET/CT scan for fever of unknown origin. MethodsThe 18F-FDG PET/CT scan results and clinical data were analyzed retrospectively in 32 patients with fever of unknown origin examined between January 2011 and October 2013. Final diagnoses were determined with recognized diagnostic standard. Results18F-FDG PET/CT scan was able to detect the cause of fever precisely in 53.1% (n=17) of the patients and was helpful in 25 patients (78.1%). The final cause of fever was determined in 20 patients, including infection (40%), malignancy (10%), non-infectious inflammatory disease (40%) and miscellaneous causes (10%). True positive, false positive, true negative and false negative rate of the modality were 17.0%, 4.0%, 8.0% and 3.0%; and the sensitivity and specificity were 85.0% and 66.7%. Conclusion18F-FDG PET/CT scan plays an important role in the diagnosis of fever of unknown origin.