Biomarkers that describe the severity and progression of COPD and the responses of patients to treatment are a desirable addition to clinical measures of disease. In this review, we describe the current state of knowledge of biomarkers used for the diagnosis, staging and therapeutic response of COPD patients. The nature of these biomarkers is considered in relation to their intended use, and the desirable qualities of such entities are examined. Examples of biased and unbiased discovery platforms for COPD biomarker discovery are given, and the major findings of these studies are discussed. Cutting edge technology used for biomarker discovery, quantitation in biofluids and imaging biomarkers in whole body systems is reviewed.