Asthma is a common long-term condition that remains poorly controlled in many people despite the availability of pharmacological interventions, evidence-based treatment guidelines and care pathways.(1) There is considerable public interest in the use of non-pharmacological approaches for the treatment of asthma.(2) A survey of people with asthma reported that many have used complementary and alternative medicine, often without the knowledge of their clinical team.(3) Such interventions include breathing techniques, herbal products, homeopathy and acupuncture. The role of breathing exercises within the management of asthma has been controversial, partly because early claims of effectiveness were exaggerated.(4) UK national guidance and international guidelines on the management of asthma have included the option of breathing exercise programmes as an adjuvant to pharmacological treatment.(5,6) Here we discuss the types of breathing exercises used and review the evidence for their effectiveness.