Background/aim: T-helper cell type 1 (Th1)/Th2 cytokine balance is involved in the resistance or susceptibility to Brucella infection. The analysis of cytokine levels is valuable to determine the role of the immune system in Brucella prognosis. The aim of this study was to investigate the levels of serum interleukin-17 (IL-17) and transforming growth factor beta (TGF-β) and their alterations with treatment in patients with acute brucellosis. Materials and methods: TGF-β was tested in 33 acute brucellosis patients and 19 controls and IL-17 was analyzed in 40 patients and 12 controls. Cytokine levels were tested in controls and patients before and after treatment by ELISA. Results: TGF-β levels were significantly lower in brucellosis cases compared to controls. At the end of the treatment, the serum levels of this cytokine had increased, but there was no significant difference between this cytokine level before and after treatment. The IL-17 level was significantly higher in the brucellosis group compared to controls and its value decreased in patients at the end of treatment without any significant difference. Conclusion: This study indicated that TGF-β was lower and IL-17 was higher in brucellosis cases and, after treatment, the serum level of TGF-β increased and that of IL-17 decreased in these patients.