We studied the effect of inhaled budesonide on bronchial hyperresponsiveness (BHR) in twenty mild asthmatic patients. The study was conducted as a randomized, double-blind, placebo-controlled study. Before entering the study, the patients performed methacholine inhalation challenge (MIC) using a reservoir method to assess BHR. Then, they were randomly allocated to receive budesonide turbuhaler (200 micrograms/dose) or placebo turbuhaler two inhalations, twice daily for eight weeks. During the study, each patient recorded daily asthma score and daily number of puffs of beta 2 agonist and they were assessed at weeks 4 and 8. At the end of the treatment, MIC was repeated again. Patients receiving budesonide showed a significant improvement in airway responsiveness compared with those receiving placebo (p < 0.05). They also showed a significant improvement in asthma severity score and a significant decrease in beta 2 agonist bronchodilator use. This study also suggested that inhaled corticosteroids may be the primary treatment in patients, even with mild asthmatic and well-controlled symptoms.