We studied 223 outpatients who presented between October 2001 and June 2003 with persistent cough of more than 3 weeks' duration. Eosinophilic airway disorders (EAD), including atopic cough and cough variant asthma, were clinically diagnosed in 119 patients, on the basis of the following factors: history of atopic disease, duration of cough, history of previous prolonged cough, or presence of forced expiration wheeze. Since eosinophils are frequently found in the sputum of patients with EAD, a positive test strongly suggests the presence of EAD. In this study, the test was positive in 86% of the patients with EAD. The patients with clinically diagnosed EAD, including those with no eosinophils in the sputum, were treated with inhaled fluticasone 400 or 800 microg/day. Fluticasone was effective in 97% of the patients with EAD and was more effective than bronchodilators or antiallergic drugs. When we compared the results of fluticasone 400 microg/day with those of 800 microg/day doses, the cough disappeared within 1 week in 28% of the patients who received 400 microg/day, whereas in 76% with 800 microg/day. Among the patients with diagnosed EAD, bronchial asthma developed in 6 patients during the observation period. Most of these patients had forced expiration wheeze and lower FEV 1 at the initial visit. This study showed that EAD could be diagnosed in the early stage on the basis of thorough history-taking, the presence of forced expiration wheeze and detection of eosinophils in the sputum. It is important to diagnose and treat EAD as early as possible since inhaled steroid is highly effective.