Background: Asthma is a major public health problem with a high economic burden. It involves several inflammatory cells and multiple mediators. Granzyme B is an inflammatory mediator expressed and secreted by both immune and non immune cells. Recently it was found to play a role in the pathogenesis of asthma.The aim of this work: was to evaluate the effect of both inhaled and oral corticosteroids on sputum granzyme B in asthmatic patients with moderate severity.Methods: The study included 25 patients with moderate persistent asthma plus 15 healthy subjects as a control group. Granzyme B was measured before treatment with corticosteroids then after inhalation therapy and oral therapy.Results: It was found that expected pulmonary function parameters were significantly lower in asthmatic patients than in controls. Sputum granzyme B levels were significantly higher in asthmatic patients than in controls. Sputum granzyme B levels were significantly lower after treatment with inhaled corticosteroids than basal levels. Oral corticosteroids further significantly lowered granzyme B, but the lowering effect of inhaled steroids was significantly higher than that of oral drugs. There was no statistically significant correlation between granzyme B and PFTs in asthmatic patients.Conclusion: Granzyme B levels are elevated in bronchial asthma. Granzyme B could play a role in the pathogenesis of bronchial asthma. Both inhaled and oral corticosteroids lowered granzyme B levels significantly. The lowering effect of inhaled corticosteroids on sputum granzyme B is more than that of the oral corticosteroids.