In order to quantify and classify ciliary changes of bronchial epithelium in chronic bronchitis, an ultrastructural study on biopsy specimens of 30 patients submitted to bronchoscopy was performed. Fourteen patients were affected by endoscopically and clinically confirmed chronic bronchitis, 8 showed an endoscopic picture of chronic bronchitis but without the clinical features of this pathology, 8 were free of chronic bronchitis. The mean percentage of abnormal cilia in control subjects (1.9 +/- 1.0%) was significantly lower than in patients either with only 'endoscopic' chronic bronchitis (5.7 +/- 2.6%; p less than 0.001) or with 'clinical' chronic bronchitis (14.8 +/- 15.9%; p less than 0.05). Like the ciliary body, the ciliary tip can also show some abnormalities. It is possible to subdivide them in two types: (1) ciliary membrane blebs; (2) ciliary membrane extrusions, variously shaped and sized, with homogeneous content. Bronchial cilia abnormalities become more serious as soon as the clinical picture worsens and this is likely to contribute to the impairment of the mucociliary clearance in chronic bronchitis patients.