BACKGROUND: It is known that airway inflammation is present in most patients with asthma, but the relationship between symptoms and the severity and nature of airway inflammation has not been established. Cough variant asthma is defined as an asthma in which the dominant symptom is cough and the condition can be successfully treated with inhaled steroids. This study was performed to evaluate the time coulee of bronchial responsiveness according to an inhaled anti-inflammatory therapy and the factors which affect the resolution of bronchial responsiveness, and an efficacy of nedocromil to cough asthma. METHOD: A prospective study for the investigation of bronchial responsiveness according to an inhaled anti-inflammatory treatment in sixty-one cough asthmatics was performed. Twenty-three entered budesonide (400microgram 2/day), twenty-two entered nedocromil (4mg2/day) and sixteen patients entered combined group. The bronchial hyperresponsiveness (BHR) was estimated by methacholine challenge test using counted breath method. The symptom was estimated by 'symptom score'. Reevaluation of BHR and symptom was performed at 2 month after treatment, and if BHR was not resoluted at this time, regarded as a non-responder, and then follow-up of BHR and symptom was performed at 4-and/or 6 month after treatment. RESULTS: The improvement of BHR and symptom was significant in 2 month (p < 0.05), but there was no change of them during follow-up period of 4-and/or 6 month in non-responders. In comparison of allergic markers such as serum total IgE, peripheral eosinophil count and skin test reactivity between responders and non-responders, there was no difference in each other. However, in comparison of other factors such as cumulative pack-years, symptom duration age, gender, and the initial degree of PC20, there was a significant difference in each other(p < 0.05). The percent of patients with the resolution of BHR in 2 month was not different in each group (p=0.95). There was no significant difference in the degree of improvement of BHR and symptom in each group. CONCLUSION: Bronchial responsiveness and symptom was not significantly improved in non-responders during follow-up period of 4-and/or 6 month. The effect of inhaled nedocromil was equivalent to that of inhaled steroid in cough asthmatics, and the response to combined treatment is not superior to that achieved by either of these agents used alone.