Objective: The aim of this study was to assess a possible relationship between temporomandibular disorders [TMD] and serum levels of sulfhydryl [SH] groups and ceruloplasmin [CP], paraoxonase-1 [PON1], and arylesterase [ARE] activities. Method: This study included patients with TMD and healthy normal controls [HNC]. After clinical and radiographic examinations, the patient group was given a visual analog scale to determine severity of pain. Serum samples of the subjects were obtained to calculate certain antioxidant components. The CP, PON1, and ARE activities and serum levels of SH groups were measured. Results: There were 31 patients with TMD and 35 HNC. Serum levels of SH and ARE activity of the TMD group were significantly lower than those of the HNC group [P 0.05]. The difference between CP and PON1 activity of the TMD and HNC groups were not statistically significant [P 0.05]. No association was found between antioxidant levels and severity of pain and the type of the TMD. Conclusions: Antioxidant components may be associated with TMD, implying possible systemic inflammatory and oxidative aspect of TMD.