Objective: The aim of the present study was to evaluate the antioxidant properties of betaine against asthma in a model of mice. Methods: Thirty-two adult female BALB/c mice were divided into four groups: control (C), asthma (A), betaine-asthma (BA), and prednisolone-asthma (PA). Intraperitoneal injection of 100 μl ovalbumin (OVA) solution on days 0, 7, 14, and 21, was administrated followed by sensitization with OVA drops in the A, BA, and PA groups. Prednisolone (3mg /kg) and betaine (1%w/w of the total diet) were administered orally once daily from day 27 to 84. Results: A significant reduction of inflammation was observed in the BA group following betaine treatment (P <0.01). IgE levels increased significantly in the A and PA groups, whereas betaine treatment led to a significant reduction in IgE concentrations (P <0.01). Betaine and prednisolone treatments significantly increased the activities of catalase (CAT), superoxide dismutase (SOD), and total glutathione levels (P <0.01). Glutathione peroxidase activity was significantly elevated in the PA group compared to the C and A groups (P <0.01). Betaine and prednisolone treatments significantly reduced the concentration of malondialdehyde (MDA) when compared to the A group (P <0.01). Conclusion: It seems, betaine as a promising dietary supplement was associated with an increase of erythrocyte antioxidant activity and a decrease of lipid peroxidation. These findings suggest that betaine may have beneficial effects, particularly in combination with prednisolone, for the treatment of asthma.