AIM:To investigate the comparison of total antioxidant capacity in the serum of patients with pterygium and control subjects.METHODS:This case-control study was conducted on all persons referred to Ophthalmology Clinic of teaching Hospital of Vali-Asr (peace upon to him) with clinical symptoms of pterygium during the year 2016.The control group was selected among patients referred to the Ophthalmology Clinic of Vaii-Asr (peace without pterygium) that the two groups were matched in terms of age,gender and place of residence.Sixty-six persons [31 people (47％) in patient group and 35 people (53％) in the control group] were enrolled by convenience sampling.Venous blood sample was taken from all patients after the sampling using ferric reducing antioxidant power(FRAP);FRAP-as a quick 10min measurement,the antioxidant power measurement of samples according to the conversion of ferric iron (Fe3+) to ferrous iron (Fe2+) was checked.The collected data ware entered to software SPSS 21 and were analyzed by chi-square and MannWhitney tests at the level of α =0.05.RESULTS:The mean of antioxidant capacity in patients was 842.55 ± 161.46 μ mol/L and antioxidant capacity in healthy controls was 856.77±209.41 μ mol/L (P=0.8).In the comparison of mean serum antioxidant capacity in healthy individuals and in the serum of people with pterygium based on gender the results showed that the antioxidant capacity mean in male control subjects has been 894.05 ± 176.82 μmol/L and in females control 780.01±118.33 μmol/L that the observed difference have been reported statistically significant (P=0.008) but the other comparison according the gender between cases and control does not show any significant difference.CONCLUSION:The results of this study showed that the full level of serum antioxidant capacity in patients has been less than the mean of antioxidant capacity in control subjects,however the observed difference has not been significant.The results of this study were consistent with basic results carried out on the damaging effects of oxidative stress in the pterygium pathogenesis.Recommending diet with minerals and vitamins containing antioxidants may be preventing the onset and progression of pterygium.