Objective: After the relationship between depression and oxidative stress (OS) was demonstrated, the effect of antidepressant drugs on OS has become important. In this study, we aimed to determine the effects of the antidepressant duloxetine on the activities of the superoxide dismutase (SOD), catalase (CAT), adenosine deaminase (ADA), xanthine oxidase (XO) and glutathione peroxidase (GSH-Px) enzymes as well as the lipid peroxidation (LP) product malondialdehyde (MDA) and nitric oxide (NO) levels in rat brains. 
 Material and Method: Twenty male Sprague-Dawley rats were used for the study. The first group was the control group (n=10) and the second group was the duloxetine group (n=10). Duloxetine was administered intragastrically once a day at a dose of 10 mg/kg for two weeks in the second group. Water was administered intragastrically once a day for two weeks in the first group. Rats were sacrificed at the end of the fourteenth day. The brain tissues were collected and then analyzes were performed.
 Results: As a result of this study, we found that duloxetine increased the SOD (P=0.026) activity and decreased the ADA (P=0.041), XO (P=0.034) and CAT (P=0.006) activities significantly compared to the control group. We also found an increase in the GSH-Px enzyme activity and decrease in the NO and MDA levels at non-significant rates in the duloxetine group brain tissues.
 Conclusion: The significant increase in the activity of the antioxidant enzyme SOD, the significant decrease in the activities of the XO and ADA enzymes, which can cause the formation of reactive oxygen products in the organism, and the insignificant decrease in the LP indicator MDA suggest that duloxetine can positively change the antioxidant status in rat brain tissues.