Lower airway obstruction commonly presents with wheezing but is not always caused by asthma. Considering the case history and course of illness is of utmost importance in determining the cause of wheezing. We present two cases admitted to the paediatric intensive care unit, in which a double aortic arch was found to be the cause of wheezing. The cases illustrate the importance of a systematic approach when investigating a patient with persistent wheeze, especially when there is a poor response to conventional therapy.