Objectives: To investigate the effects of a peroxisome proliferator-activated receptor-gamma (PPAR-γ) agonist, rosiglitazone, on induced bronchial asthma in a murine model. Material and methods: Adult male guinea pigs were administered ovalbumin 100 mg/kg S.C. and 100 mg/kg I.P. Treatment with rosiglitazone (5 mg/kg/day, PO) was assessed for 21 days. On day 21, the animals were challenged with the same dose of ovalbumin and the ratio of FEV1 (forced expiratory volume in one second) to FVC (forced vital capacity), FEV1/ FVC, was measured using a spirometer. In addition, serum levels of interleukin-5 (IL-5) and immunoglobulin E (IgE) were assessed. The activities of superoxide dismutase (SOD) and catalase and the level of reduced glutathione (GSH) were determined in lung tissue homogenates. Furthermore, histopathological examination of the lung was performed. Results: treatment with rosiglitazone resulted in a profound improvement in lung function and histopathological features. These improvements were accompanied by a significant decrease in the serum levels of IL-5 and IgE. Moreover, the activities of antioxidant enzymes, including SOD and catalase, and the GSH level were significantly increased in the lung tissues of treated animals compared to those of untreated asthmatic animals. Conclusion: PPAR-γ agonist rosiglitazone may have potential in the development of therapies for bronchial asthma.