The aim of this study was to determine the clinical effect of inhaled corticosteroid treatment for persistent cough, post upper respiratory tract infection (URTI) in previously healthy individuals, and on bronchial hyperresponsiveness (BHR). This was a prospective, randomized, double-blinded, placebo-controlled study conducted at a university hospital. A total of 30 non-asthmatic, non-smoking patients who were >15 years old and who had persistent post-URTI cough for >3 weeks were assessed by a physical examination, CXR and spirometry, and were allocated to receive inhaled budesonide (400 microg/puff, twice daily) or placebo for 4 weeks. If a patient suffered from sinusitis, it was a requirement that it had been well treated. A symptom score (frequency of cough, frequency of coughing bouts, symptoms associated with cough, night-time cough, frequency of taking medications to relieve cough, and number of medications) was recorded at entry, and after 2 and 4 weeks of treatment. A methacholine challenge test was performed at entry and after 4 weeks of treatment. The mean symptom scores for the treatment group (9.4) and the placebo group (9.8) at baseline were not significantly different (P=0.79), and no differences were found between the groups after week 2 and week 4 of treatment (3.93 and 4.27 vs 2.26 and 2.66, P=0.29). The mean change in symptom scores from baseline to week 2 and to week 4 of treatment were also not different between groups (5.93 and 5.6 vs 7.00 and 7.58, P=0.23). No difference between groups was found in the mean changes in FEV(1), FVC, and FEF(25--75%) after 4 weeks of treatment. A positive bronchial provocation test occurred in three patients (10%) but these were borderline. Inhaled corticosteroid is ineffective in treating persistent post-URTI cough in previously healthy individuals.