BACKGROUND: Cough Coughing is the most common complaint for which patients seek medical service. When cough sustains caughing continues over 3 weeks in non-smokers who do not take cough-provoking drugs, they are classified as patients with chronic cough. As well-known, three Three well known main causes of chronic caugh are diseases - (delete) postnasal drip syndrome, bronchial asthma and gastroesophaseal reflux disease. - comprise the majority of the causes of chronic cough. Among them, postnasal drip syndrome is reported to be the most common cause of all in chronic cough diseases, and allergic inflammation plays an important role in the pathogenesis of postnasal drip syndrome. CD23 and CD25 which are low affinity receptor for IgE and IL-2 receptor alpha, respectively, are closely related to allergic inflammation and we evaluated the role of them in their roles were evaluated in chronic cough patients. METHODS: We evaluated 105 patients with chronic cough and selected 56 patients for measurement of serum CD23