Despite the importance of cigarette smoking as a cause of respiratory symptoms and disease, until recently there has been little attention on the effect of smoking on cough reflex sensitivity. Recent studies have shown that in otherwise healthy smokers, cough reflex sensitivity is diminished relative to that of nonsmokers. One proposed mechanism, chronic cigarette smoke-induced desensitization of airway cough receptors, is supported by the demonstration that smoking cessation leads to prompt enhancement of cough reflex sensitivity, even after many years of smoking. Furthermore, resumption of cigarette smoking promptly results in suppression of cough reflex sensitivity. These observations have introduced the concept that cough reflex sensitivity in humans is a dynamic phenomenon, able to be modulated by the presence or absence of stimuli such as cigarette smoke, even after prolonged exposure.