Objective: The pathogenesis of Behçet’s disease (BD) may be related to excessive production of reactive oxygen species, activated neutrophils, and T lymphocytes. The goal of this prospective study was to investigate whether there is any relationship among the oxidant/antioxidant system and nitric oxide (NO) and malondialdehyde (MDA) levels in patients with BD and its subtypes: complete Behçet’s disease (CBD) and incomplete Behçet’s disease (ICBD), with or without ocular disease. Methods: Thirty-two patients and 26 age- and sex-matched healthy control subjects were evaluated for NO and MDA levels and antioxidant enzyme activities. The patients with BD were divided into two subgroups: those with and without ocular disease. Twelve patients with CBD and 4 patients with ICBD had ocular disease. The serum NO level was determined by Griess reaction. The MDA level was detected by thiobarbituric acid reaction. Superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities in serum were analyzed with spectrophotometric methods. Results: Increased MDA levels but decreased GSH-Px activities in plasma were observed in BD patients with all subtypes, as compared with controls. Concerning the presence of ocular disease and the subtype (CBD or ICBD) compared with each other, there were no significant differences in MDA or NO serum levels and SOD or GSH-Px enzyme activities. Conclusions: Serum NO levels and SOD enzyme activities were not significantly changed in patients with BD and its subtypes; however, a remarkable decrease of GSH-Px enzyme activity and increase of MDA levels were found.