Aim: To investigate whether cytokines are effective in predicting relapses among patients with acute brucellosis. Materials and methods: This trial was conducted in 42 patients who were being followed-up with diagnosis of acute brucellosis. Serum samples were obtained on days 0 and 45. In patients whose clinical symptoms recurred within a year of treatment and exhibited infectious parameters in compliance with brucellosis, a Rivanol standard tube agglutination (STA) test was performed and the diagnosis of relapse was based on brucella immunoglobulin M (IgM). Serum samples were evaluated for various parameters, namely tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ), interleukin 2 (IL-2), IL-4, IL-6, IL-8, IL-10, and soluble IL-2 receptor (sIL-2R). Results: Relapse was seen in 7 patients. No difference was found between relapsing patients (RPs) and fully recovered patients (FRPs) in terms of age, sex, leukocyte levels, or C-reactive protein (CRP) values. Comparison of TNFα, IFNγ, IL-2, IL-4, IL-6, IL-8, and IL-10 values on day 0 (day of enrollment) revealed 2-fold higher IL-8 values among RPs compared to FRPs. IL-8 was suggested as significant in terms of predicting relapse. Conclusion: Diagnosis and treatment of relapsing cases in acute brucellosis have not yet been clarified. Predicting relapse by certain laboratory evaluations may be beneficial in preventing clinical relapses by rearranging treatment and monitoring strategies of patients. © TÜBİTAK.