Thirty-nine subjects were included in this double-blind, placebo-controlled study of bronchial hyperresponsiveness (BHR) in patients with mild to moderate asthma. The time-courses of change of FEV1, PEFR%, bronchial reactivity, and daily measures of asthma control were determined during 8 weeks of treatment after a run-in period of 2 weeks. Bronchial hyperresponsiveness was assessed by the methacholine provocation method, defined as the dose of methacholine causing a 20% fall of FEV1 compared with baseline values. The trends of FEV1 and the percentage change in PEFR from baseline were significantly different between groups, in favor of budesonide (P < .05). Patient assessments of the effect of treatment showed that PEF improved significantly in the budesonide group only. The budesonide group increased their tolerability for methacholine provocation by 1.8 DD (doubling dose), which tended to be higher compared with the 0.8 DD of the placebo group. It is evident from this study and previous studies that more data are needed to establish the dose-effect relationship with time and severity of the disease.