We proposed to assess antioxidant status and nitric oxide in fibromyalgia (FM) patients in comparison to healthy controls. Additionally, the association between the serum antioxidant levels and clinical findings in FM patients was also investigated. Thirty-seven FM patients and 37 healthy controls were enrolled in this study. Severity of fatigue and pain were determined by Visual Analogue Scale. Functional capacity in daily living activities was evaluated by fibromyalgia impact questionnaire. Serum NO, catalase and glutathione were measured. Serum glutathione and catalase levels were significantly lower in FM patients than controls. However, no significant difference was seen in serum NO levels between the two groups. A significant correlation was evident between serum NO level and pain. Additionally, the correlation between glutathione level and morning stiffness was found to be significant. These findings support other studies, we assume that these two antioxidants might have impact on the pathogenesis of FM disease.