Objective:It was aimed to investigate the clinical and laboratory changes in complicated and uncomplicated brucellosis cases.Method:Within the scope of the study, 268 brucellosis patients (aged ≥18 years) hospitalized in the infectious diseases unit or seen in outpatient clinics were evaluated retrospectively. The complicated and uncomplicated brucellosis cases were assessed.Results:In the study, 268 brucellosis patients were evaluated and it was observed that 80.7% of the patients consumed fresh cheese. Also, 93.2, 90.8, 88.8 and 84% of the cases had symptoms such as arthralgia, weakness, sweating and fever, respectively. Anemia, leukopenia, leukocytosis, thrombocytopenia and increased C-reactive protein (CRP) were also detected in 25.9, 4.9, 7.2, 9.2 and 60.2% of patients, respectively. It was found that 32.4% of the patients developed complications, and the complications were osteoarticular in 59 patients (67.8%), genitourinary in 17 (19.5%) and hematological in three (3.44%) cases. The complications were more common in male patients. CRP and neutrophil/lymphocyte ratios (NLR) were also found higher in complicated cases.Conclusion:Since values such as gender, CRP and NLR were significantly different in complicated brucellosis cases from the noncomplicated group, it is considered that a significant increase may have been detected in infection parameters due to the longer exposure time to the microorganism. For this reason, early detection of complications and timely diagnosis play a vital role to improve the prognosis.