Breathlessness is frequent in the hospital setting: almost 50% of seriously ill hospitalised patients complain of dyspnoea, and its presence aggravates morbidity and mortality. Evaluation of breathlessness, based on self-report, must be completed with the measurement of vital signs and with a search for clinical signs of serious problems - desaturation, stridor, use of accessory muscles or alteration of mental status - that need urgent treatment. After this first therapeutic step, the diagnostic strategy consists of a multidisciplihary approach to determine the physiopathological mechanisms of dyspnoea that will determinate its final management.