The effects of Curcuma longa (C. longa) and curcumin on total and differential WBC count and oxidant, antioxidant biomarkers, in rat model of asthma were evaluated. Materials and Methods: Total and differential WBC count in the blood, NO2, NO3, MDA, SOD, CAT and thiol levels in serum were examined in control, asthma, Asthmatic rats treated with C. longa (0. 75, 1. 50, and 3. 00 mg/ml), curcumin (0. 15, 0. 30, and 0. 60 mg/ml), and dexamethasone (1. 25 μ g/ml) rats. Results: Total and most differential WBC count, NO2, NO3 and MDA were increased but lymphocytes, SOD, CAT and thiol were decreased in asthmatic animals compared to controls (P<0. 001). Total WBC, NO2 and NO3 were significantly reduced in treated groups with dexamethasone and all concentrations of C. longa and curcumin compared to asthmatic group (P<0. 001 for all cases). MDA was significantly decreased, but SOD, CAT and thiol increased in treated asthma animals with dexamethasone and two higher concentrations of C. longa and curcumin (P<0. 01 to P<0. 001). There were significant improvement in eosinophil percentage due to treatment of highest concentration of the extract and curcumin, neutrophil and monocyte due to highest concentration of curcumin and lymphocyte due to highest concentration of the extract and two higher concentrations of curcumin compared to asthmatic group (P<0. 01 to P<0. 001). Dexamethasone treatment improved monocyte (P<0. 001) and lymphocyte (P<0. 01) percentages. Conclusion: Antioxidant and anti-inflammatory effects of C. longa extract and its constituent curcumin in animal model of asthma was observed which suggest a therapeutic potential for the plant and its constituent on asthma.