Objective: Sildenafil, which is used for the treatment of erectile dysfunction, has been shown to inhibit inflammation in an animal model of asthma. We aimed to determine the impact of nebulized sildenafil on lung histology in a murine model of chronic asthma. Material and Methods: Forty-two BALB/c mice were divided into six groups; A, B, C, D, E, and the control group. All groups except controls were sensitized and challenged with ovalbumin. Then, mice in Group A received nebulized saline. Nebulized sildenafil citrate was administered to Group B, C, and D at concentrations of 0.035 mg/ml, 0.07 mg/ml, and 0.105 mg/ml respectively, and nebulized budesonide was administered at a concentration of 0.25 mg/ml to Group E for 15 minutes once a day, for a week. Animals were sacrificed 24 hours after the last inhalational exposure and the airway samples were evaluated histologically by light and electron microscopy. Results: All the histologic parameters of asthma in Group B were significantly ameliorated when compared to the ones in Group A. In Groups C and D, all the parameters except thicknesses of subepithelial smooth muscle layers were significantly improved when compared to Group A. Thicknesses of basement membrane, subepithelial smooth muscle, and epithelium were significantly smaller in Group B than Group E. Thicknesses of basement membrane and subepithelial smooth muscle were significantly smaller in Group C than Group E. Thickness of subepithelial smooth muscle was significantly smaller in Group D than Group E. Conclusion: The responses regarding improvement in asthma pathology were found better with all doses of nebulized sildenafil than placebo and even nebulized steroid.