We describe the use of high-resolution computed tomography (HRCT) for assessment of the function of pulmonary vessels and airways. With its excellent spatial resolution, HRCT is able to demonstrate pulmonary structures as small as 300 microns and can be used to monitor changes following various stimuli. HRCT also provides information about structures smaller than 300 microns through measurement of parenchymal background density. To date, sequential, spiral and ultrafast HRCT techniques have been used in a variety of challenges to gather information about the anatomical correlates of traditional physiological measurements, thus making anatomical-physiological correlation possible. HRCT of bronchial reactivity can demonstrate the location and time course of aerosol-induced bronchoconstriction and may show changes not apparent on spirometry. HRCT of the pulmonary vascular system visualizes adaptations of vessels during hypoxia and intravascular volume loading and elucidates cardiorespiratory interactions. Experimental studies provide a basis for potential clinical applications of this method.