The cause of dyspnoea is not always obvious at the first bedside assessment. In such cases, some sort of a structured approach is required. This chapter discusses how a systemic approach to dyspnoea may be formulated. Such an approach not only facilitates narrowing of the differential diagnosis but also clarifies the underlying mechanisms of disease. Since the components of the approach to dyspnoea are shared with those of respiratory failure, it is recommended that this section be read in conjunction with the chapter on respiratory failure (Chap. 6 ).