Over 300 million people suffer with asthma worldwide and it has emerged that microbiome analysis of the lung and gut bacteria, fungi, viruses, and archaea may help with disease management. This microbiome plays an important role in immune response. Disturbances to these microbes, known as dysbiosis, may influence onset of disease and the body’s ability to respond naturally, and/or to pharmaceutical treatments. Asthma is not a singular disease and there are great variations in symptom severity and underlying immune mechanisms. Patients are typically classified as type 2 or non-type 2. Type 2 patients tend to be allergic to common air-born allergens which can trigger an attack. Treatment usually consists of glucocorticosteroids or novel biologicals. Non type-2 asthma is associated with obesity-related asthma and typically responds poorly to steroid treatment. For a long time, researchers believed the human lungs to be sterile, so they were initially not included in the 2007 Human Microbiome Project. It has since been shown that, like the gut, the lungs and respiratory tract also host various microbes, and this healthy-airway microbiota influence innate and adaptive immune processes. The Gut-Lung axis also confers additional microbial benefits from the intestines. In asthma patients, there is often an over-dominance of pathogenic bacteria. Fungal dysbiosis is associated with high-risk asthma phenotypes in childhood. Viral infections have been shown as a primary cause of asthmatic episodes. Future diagnosis and treatment of patients with asthma should be assisted by analysis of the composition and metabolic activity of an individual’s microbiome.