Expiratory HRCT is a powerful adjunct to inspiratory HRCT for detecting various small airway diseases. Current standard expiratory HRCT protocol consists of a limited number of non-contiguous scans at selected levels. We have developed a new volumetric expiratory HRCT protocol that allows volumetric data acquisition of lungs both at end-inspiration and end-expiration. By reducing the x-ray tube current, the radiation dose of this new protocol is equivalent to the standard expiratory HRCT protocol at our institution. This volumetric expiratory HRCT has been applied in patients with diffuse lung disease with small airway abnormalities. In this review, we describe: (1) technical considerations of VEHRCT including dose reduction, (2) the advantages of contiguous scans and multiplanar reformations, (3) clinical application of volumetric expiratory HRCT in various diffuse lung diseases, and (4) future directions including computational qualitative assessment of lung biomechanics.