In this study, we investigated the pro- and antioxidant status of patients with a pathogenesis of Crimean-Congo hemorrhagic fever (CCHF) in terms of their role in its pathogenesis. During the study period, 34 children and 41 adults were diagnosed with CCHF. The control group consisted of healthy age- and gender-matched children and adults. Serum levels of the total antioxidant capacity (TAC), total oxidant status (TOS), oxidative stress index (OSI), and plasma total thiol (TTL) were evaluated and compared between groups. The difference in mean TAC values between CCHF patients and healthy controls was not statistically significant (P > 0.05). Mean TOS, OSI, and TTL values were significantly lower in CCHF patients than in healthy controls (P < 0.001). Comparisons between the 2 groups revealed that mean TOS and OSI values were significantly lower in adults with CCHF than in their healthy counterparts (P < 0.001). Similarly, mean TTL levels were lower in both children and adults with CCHF when compared separately with healthy controls (P < 0.05). There was no significant difference in the mean serum TTL levels between children and adults with CCHF (P > 0.05). Our results suggest that TTL may play a more important role in CCHF pathogenesis than the other parameters investigated. The mean TOS and OSI values were higher in the control group than in CCHF patients.