Abstract: Objective To investigate the etiology features of patients with fever with unknown origin（FUO） in Chongqing in recent years,and provide reference for clinical diagnosis and treatment of FUO.Methods the data of 548 inpatients who met the criteria for FUO in the department of infection of the first affiliated hospital of Chongqing medical university from 2017 to 2019 were retrospectively summarized and analyzed,and the etiology of FUO patients was classified.Results 548 patients were diagnosed with 371 cases after various examinations and diagnostic treatments,with a confirmed rate of 67.8%.There were 285 cases of infectious diseases (52.0%),14 cases of neoplastic diseases (2.6%),47 cases of connective tissue diseases (8.6%),25 cases of other diseases (4.6%),and 177 cases of undiagnosed diseases (32.2%) at the time of discharge.Conclusions The etiology of patients with fever is unclear,infectious diseases are still the main cause of fever,followed by undiagnosed diseases,connective tissue diseases,other diseases,and neoplastic diseases at the time of discharge.

Key words: Fever of unknown origin, Infectious diseases, Causes analysis