Dyspnoea has been described as ‘a subjective awareness of the sensation of uncomfortable breathing’ (Coccia et al., S Afr Med J 106(1):32–6, 2016). Multiple versions of the definition exist, but since the sensation is a symptom and not a sign, the description of dyspnoea is inevitably coloured by the patient’s perception. Dyspnoea may be perceived as fatigue, weakness or even chest pain, which further compounds the difficulties in its analysis. Dyspnoea occurs when the homeostasis of the pulmonary and cardiac systems is disturbed, but may also be seen in disturbances pertaining to the circulatory and neuromuscular systems as well as in those that are metabolic or psychogenic (Coccia et al., S Afr Med J 106(1):32–6, 2016). The approach to dyspnoea is therefore multi-pronged and often difficult. This chapter discusses how the cause of dyspnoea may be identified based on its characterisation, and the various nuances of this common symptom of respiratory disease.