Introduction: Brucellosis and Crimean-Congo Hemorrhagic Fever (CCHF) are diseases that can present with similar clinical and laboratory findings to those of COVID-19, leading to misdiagnosis or confusion by visiting multiple departments. This can delay diagnosis and increase the risk of nosocomial transmission in the case of CCHF. Although misdiagnosis of Brucellosis and CCHF, and even a case of coinfection have been reported in the literature, no case report mentioning CCHF and Brucellosis coinfection hospitalized with the pre-diagnosis of COVID-19 was found. Case Report: A 35-year-old female patient presented to the emergency service with complaints of fever and fatigue. The patient was evaluated in the emergency triage and was taken to the area where COVID-19 pre-diagnosed patients were being examined. A thorax computed tomography (CT) without intravenous contrast usage was reported as normal, and the patient was discharged after being informed about COVID-19 transmission routes. The patient re-applied to the emergency service with complaints of fever, fatigue, headache, and myalgia four days later. The laboratory findings showed a white-cell count of 1600/mm³, haemoglobin of 12.8 g/liter, platelet of 146000/mm³, urea of 21.5 mg/dl, creatinine of 0.81 mg/dl, alanine aminotransferase (ALT) of 134 U/liter, aspartate aminotransferase (AST) of 303 U/liter, lactate dehydrogenase (LDH) of 714 U/liter, creatine kinase (CK) of 1796 U/liter, C-reactive protein (CRP) of 3 mg/liter, D-dimer of 2000 µg/liter, and a thorax CT showed minimal ground-glass opacity. The patient was hospitalized with a preliminary diagnosis of COVID-19 by the chest diseases clinic. Conclusion: A patient with Brucellosis and CCHF coinfection was hospitalized with a preliminary diagnosis of COVID-19. This case highlights the importance of considering other diseases with similar clinical and laboratory findings in endemic regions of Brucellosis and CCHF to avoid misdiagnosis and delay in treatment. Early diagnosis and appropriate management are crucial for improving patient outcomes and preventing nosocomial transmission. References: 1. Zhu J, Ji P, Pang J, et al. (2020), Clinical characteristics of 3,062 COVID‐19 patients: a meta‐analysis. J Med Virol. Accepted Author Manuscript. doi:10.1002/jmv.25884 2. Özer S, Oltan N, Gencer S. Bruselloz: 33 olgunun değerlendirilmesi. Klimik Derg 1998; 11(3): 82-4. 3. Karakecili F, Cikman A, Aydin M, et al. Evaluation of epidemiological, clinical, and laboratory characteristics and mortality rate of patients with Crimean-Congo hemorrhagic fever in the North east region of Turkey. J Vector Borne Dis 2018;55:215-221. 4. Young EJ. Brucella species. In: Mandell GL, Bennett JE, Dolin R, eds. Mandell, Douglas and Bennett's Principles and Practice of Infectious Diseases. 6th ed. Churchill Livingstone, Philadelphia, 2005:2669-74. 5. Almış H, Yakıncı C. A case of brucellosis misdiagnosed as Crimean-Congo hemorrhagic fever. Mikrobiyol Bul 2012;46(3):475-9. 6. Pappas G, Akritidis N, Bosilkovski M, Tsianos E. Brucellosis. N Engl J Med 2005;352(22):2325-36. 7. Uyar Y, Carhan A, Albayrak N, Altaş AB. Evaluation of PCR and ELISA-IgM results in the laboratory diagnosis of Crimean-Congo haemorrhagic fever cases in 2008 in Turkey. Mikrobiyol Bul 2010;44(1):57-64. 8. Vashakidze E, Mikadze I. Epidemiology, clinical and laboratory features of Crimean-Congo hemorrhagic fever in Georgia. Georgian Med News 2015;(247):54-8. 9. Cevik MA, Erbay A, Bodur H, et al. Clinical and laboratory features of Crimean-Congo hemorrhagic fever: predictors of fatality. Int J Infect Dis 2008;12(4):374-9. 10. Karakecili F, Cikman A, Akin H, Gülhan B, Özçiçek A. A case of brucellosis and Crimean-Congo hemorrhagic fever coinfection in an endemic area. Mikrobiyol Bul 2016; 50(2):322-7.