In conclusion, the findings of our study demonstrate that pitavastatin inhalation attenuates AHR, improves airway remodelling and lung pathology, increases CD4+ CD25+ Foxp3+ Treg cell numbers and balances the cytokines secreted by Th1 and Th2 cells in the lungs of mice with asthma and suggest that pitavastatin, whose properties make it suitable for delivery as an inhaled agent, may be a useful anti-inflammatory agent in the treatment of airway inflammatory diseases. This evidence concerns the gene CD4 and asthma.