Various diseases can cause bronchiectasis as a result of inflammatory bronchial wall damage. The diagnosis is based on imaging techniques, which are also required to assess the extent and localization of dilated bronchi and possible causes. Chest radiography only occasionally allows the diagnosis of bronchiectasis (Fig.2) and is usually not a sufficient basis for therapeutic decisions (Fig. 1a), but it is important for follow-up studies. Bronchography (Fig.1b) was considered the diagnostic procedure of choice in suspected bronchiectasis for decades. Being an invasive procedure, it has recently been almost completely replaced by computed tomography (CT), which can also demonstrate associated pulmonary abnormalities (Fig.6) in addition to visualizing the bronchi. CT diagnosis of bronchiectasis is based on the demonstration of bronchial dilatation relative to the adjacent pulmonary artery (Figs. 4, 5, 7-9), lack of bronchial tapering (Figs. 3, 4, 10) and visualization of bronchi in the lung periphery (Figs. 3, 5, 8, 10). In suspected bronchiectasis high-resolution scans should be obtained during inspiration. Contiguous, thicker slices or scans taken during expiration may be required in particular cases.