Beyond the bronchial dilatations associated with age, several studies have documented a higher prevalence of bronchiectasis in patients with severe asthma or chronic obstructive pulmonary disease (COPD). Perhaps COPD or asthmatic patients with bronchiectasis represent a clinical phenotype characterised by greater clinical and functional severity, a higher number of exacerbations and, in the case of COPD, greater colonisation by potentially pathogenic microorganisms and probably a poor prognosis. Although international guidelines recommend that the two diseases are treated separately when they coexist, patients with COPD or asthma associated with bronchiectasis may benefit from specific treatments, such as long-term antibiotics, physiotherapy or macrolides. It is biologically plausible that severe asthma, and especially severe COPD, are related to de novo bronchiectasis, but no study has yet demonstrated any cause-effect relationship. Early diagnosis and treatment of bronchiectasis in COPD and asthma could be crucial to improve their prognosis. This relationship poses an interesting scientific challenge for the future. (BRN Rev. 2017;3:178-91)