Objective To investigate serum antioxidant status in subjects with metabolic syndrome (MS) and analyze the association between serum antioxidant status and MS components.MethodsA case-control study was conducted with 221 MS cases and 329 controls aged 18-70 years. Weight, height, body mass index, waist circumference, blood pressure, fasting blood glucose and lipids, as well as serum superoxide dismutase (SOD), glutathione peroxidase(GSH-Px), malondialdehyde (MDA), vitamin E,β-carotene and lycopene were examined.Results Mean serum SOD activity,β-carotene level were significantly lower, and MDA higher (P<0.05) in MS subjects than in controls after adjusting for age and gender. Serum SOD, GSH-Px andβ-carotene level were also decreased significantly (P<0.05) with increased number of MS components.Conclusion Serum antioxidant status was negatively correlated with risks of MS and lower SOD activity andβ-carotene level appeared to be associated with more MS components. Serum oxidative status is useful in assessing the severity of MS.