Abstract: Objective To investigate the causes of chronic cough in Chinese patients with chronic cough and assess the efficacy of specific therapy.Methods Adopting a diagnostic protocol distribution of cough receptors designed by Irwin,and additional cytological assay of sputum,we made etiological diagnoses of the chronic cough and treated the patients with specific therapy.We got the sputum of the patients who could not expectorate by a way of inhaling 5% hypertonic saline.The patients who complained of cough 3 weeks or longer,age≥14,nonsmoking or had given up smoking ≥4 weeks and with normal chest X-ray were enrolled into our study in the time period of July 2004 to February 2005.Results Definite diagnosis was made in 114 out of the 125 patients with chronic cough.The causes included cough variant asthma,29/125,(23.2)%,postnasal drip syndrome,28/125,(22.4)%,post infectious cough,23/125,(18.4)%,gastroesophageal reflux,16/125,(12.8)%,cough induced by angiotension-converting enzyme inhibitor,15/125,(12%),eosinophilic bronchitis,3/125,(2.4)%.The causes of chronic cough in 11 patients(11/125,(8.8)%) had not been diagnosed.After treatment with specific therapy based on diagnosis,cough disappeared in 107 patients((93.9)%) and alleviated in 7 patients((6.1)%).Conclusion The diagnostic protocol based on the anatomy and distribution of cough receptors designed by Irwin,as well as cytological assay of sputum are the important methods in the diagnosis of chronic cough.Cough variant asthma,postnasal drip syndrome,post infectious cough,cough induced by angiotension-converting enzyme inhibitor,gastroesophageal reflux,and eosinophilic bronchitis are the most common causes of chronic cough.And specific therapy based on diagnosis is effective.

Key words: chronic cough, etiology, diagnosis, treatment