Although respiratory changes induced by tobacco smoke have been extensively described, no study has focused on ciliary abnormalities associated with chronic smoking. Ciliary ultrastructure was studied in 37 adults with chronic sputum production (CSP) consisting of 13 current smokers (Group 1), 5 ex-smokers (Group 2), and 19 nonsmokers (Group 3). Five healthy nonsmokers constituted the control group (Group 4). Clinical and radiologic data and respiratory function tests were recorded. Acute respiratory infection was diagnosed by culture of tracheobronchial secretions obtained during bronchoscopy. Bronchial ciliated cells were obtained and processed for transmission electron microscopy. Within each group, the percentages of abnormal cilia were similar in patients with either chronic bronchitis or bronchiectasis and in patients with or without acute infection. The percentage of axonemal ultrastructural abnormalities (AUA) was higher in smokers (16.5% +/- 2.7%) and ex-smokers (17.5% +/- 7%) than in nonsmokers (5.2% +/- 1%) or control subjects (0.7% +/- 0.2%) (p < 0.0002). The AUA were polymorphic, characteristic of acquired ultrastructural changes. These results suggest that chronic smoking may induce an increased number of abnormal cilia which could participate in impairment of tracheobronchial clearance and which appears to be independent of the etiology of CSP.