The objective was to determine the prevalence of bronchial diverticula in smokers on thin-section CT and the relationship to clinical and other morphological features on CT. Thin-section CT images of 503 cigarette smokers were assessed for the profusion and location of diverticula in the major airways. The extent of the bronchial diverticula was recorded as follows: grade 0, none; grade 1, one to three diverticula; grade 2, more than three diverticula. The extent of emphysema, bronchial wall thickness, clinical features, and pulmonary function were compared in the sub-groups stratified according to the extent of bronchial diverticula. A total of 229/503 (45.5%) smokers had bronchial diverticula, with 168/503 (33.3%) and 61/503 (12.2%) having grade 1 and 2 bronchial diverticula respectively. Subjects with grade 2 bronchial diverticula were heavier smokers, reported a history of coughing more frequently, and showed more severe functional impairment, greater extent of emphysema and more severe bronchial wall thickening compared with subjects with grade 1 and those individuals without bronchial diverticula (P < 0.05). Multivariate regression analysis revealed that only bronchial wall thickness predicted the extent of the bronchial diverticula (P < 0.0001). Bronchial diverticula are a frequent finding in the major airways of smokers, and they are associated with other markers of smoking-related damage.