Using CT to define phenotypic abnormalities in patients diagnosed as having chronic obstructive pulmonary disease (COPD) may serve to optimize treatment, guide the prognosis and assess response to potential therapeutic interventions. Objective/method: Although the different morphologic abnormalities seen on CT scans of COPD patients often overlap, two separate groups of patients can be identified, those with emphysema predominant disease and those with airway predominant disease due to chronic inflammation with resulting in airway remodelling and narrowing. The former category can be subdivided further based on the type of emphysema present and characterized further by anatomic distribution and severity using visual assessment and volumetric quantitative CT techniques. Patients in the airway predominant category can also be characterized by CT as showing bronchial wall thickening, small airway inflammation, mosaic perfusion and air trapping expressing small airway narrowing, and expiratory bronchial collapse due to cartilage deficiency. Recent advances in automated airway segmentation and quantitative analysis have made measurements of airway dimensions feasible. Conclusion: In longitudinal studies, standardization of procedures and quality control are needed, particularly if quantitative CT outcomes are used as end point in clinical trials and ultimately in the clinical management of individual patients.