The bronchial arteries, which provide the systemic arterial supply to the lungs, are involved in a variety of disease processes in humans, including congenital disorders, infection, and pulmonary thromboembolism. In these conditions, the bronchial arteries hypertrophy and bronchial blood flow increases. Consequently, in many disorders, such as bronchiectasis, the bronchial arteries are a frequent source of haemoptysis, which may be massive and life-threatening. Evaluation of the bronchial circulation has typically required invasive imaging with angiography to determine the location of bleeding. Non-invasive assessment of bronchial arterial anatomy and morphology is currently being investigated with the use of helical computed tomography (CT). We evaluated eight patients with various lung diseases with helical CT (GE Medical Systems, LS16, Milwaukee, WI) to determine the imaging features of the bronchial circulation. Non-ionic contrast medium (iopromide) was injected intravenously (80-1000ml/30s) and scanning was triggered once contrast material was present in the pulmonary artery (average delay=15s) or ascending aorta (average delay=20s). Detector collimation (16-row unit) was 10mm. Imaging parameters included a section thickness of 0.6mm, kilovolt peak of 120, 150-440mA, pitch factor of 1.375, matrix of 512x512, and tube rotation time of 0.8s. The images were reconstructed and scanned isotropically (Advantage Workstation 4.1,GE Medical Systems). We conclude that helical computed tomography may provide a non-invasive means of evaluating the bronchial arteries and their role in pulmonary disease processes.