Abstract: Objective To improve the clinical diagnosis of upper respiratory tract infection(URTI) in patients with fever of unknown origin(FUO) by analyzing its clinical features. Methods The clinical data about URTI patients with FUO admitted to our department from February 2009 to December 2012 were retrospectively analyzed. The patients were divided into groups of sex(male and female) and age(<40 years and ≥ 40 years). Their clinical data were compared. Results Fifty-eight URTI patients were enrolled in this study with a mean age of 38.6 years and a mean fever time of 25.1 days. URTI was manifested as intermittent fever in 75.9% of the patients. No significant difference was found in gender. More time and expense of diagnosis were observed in age ≥ 40 year's group(P=0.007 7, P=0.000 0). Conclusion The symptoms and signs of URTI which is manifested as chronic FUO are atypical and most of them are selflimited. The fear and medical cost of such patients can be reduced if it is early diagnosed.