Aim: This study aimed to evaluate the oxidant/antioxidant status of patients treated for brucellosis and to determine the effects of a combination of antimicrobial agents (doxycycline, streptomycin and rifampicin) that could be used in the treatment of brucellosis. Material and Methods: Sixty (60) acute patients with brucellosis and thirty (30) healthy volunteers were enrolled in the study. Doxycycline-streptomycin (DOX-STR) and doxycycline-rifampicin (DOX-RIF) were used in the treatment of brucellosis. MDA levels, total oxidant status (TOS), and superoxide dismutase, catalase levels and total antioxidant capacity (TAC) were determined in patients treated with brucellosis. Also, TOS/TAC index (OSI) was calculated. Results: Before therapy, MDA, TOS, SOD, catalase levels and OSI value were significantly higher, and TAC was significantly lower in brucella patients compared with healthy subjects (p < 0.001). After therapy, MDA, TOS, SOD, catalase levels, and OSI value significantly decreased, and plasma TAC levels significantly increased compared to the pre-treatment group, especially in the DOX-STR regimen (p < 0.001). Discussion: Over-production of oxidants and depletion of TAC in patients with brucellosis are associated with inflammatory nature of brucellosis. Measurement of oxidant/antioxidant status may be useful for monitoring patients who are recovering, and the treatment of patients with antibiotic combination, especially (DOX-STR) will ameliorate their antioxidant system.