The use of imaging technologies has progressed beyond the depiction of anatomic abnormalities to providing non-invasive regional structure and functional information in intact subjects. These data are particularly valuable in studies of the lung, since lung disease is heterogeneous and significant loss of function may occur before it is detectable by traditional whole lung measurements such as oxygenation, compliance, or spirometry. While many imaging modalities are available, X-ray computed tomography (CT) is emerging as the preferred method for imaging the lung because of its widespread availability, resolution, high signal/noise ratio for lung tissue, and speed. Utilizing the quantitative density and dimensional information available from conventional CT images, it is possible to measure whole and regional lung volumes, distribution of lung aeration and recruitment behavior under various clinical conditions and interventions, and important regional mechanical properties. In addition, using the radiodense gas xenon (Xe) as a contrast agent, regional ventilation or gas transport may also be obtained. This communication will review recent advances in CT based techniques for the measurement of regional lung function.