Asthma is a disorder of the airways characterized by chronic airway inflammation, hyperresponsiveness, and variable recurring airway obstruction. Treatment options for asthma include pharmacological strategies, while non-pharmacological strategies are limited. Established pharmacological approaches to treating asthma may cause unwanted side effects and do not always afford adequate protection against asthma, possibly due to an individual's variable response to medications. A potential non-pharmacological intervention that is most available and cost-effective is inspiratory muscle training (IMT), which is a technique targeted at increasing the strength and endurance of the diaphragm and accessory muscles of inspiration. Studies examining the impact of IMT on asthma have reported increases in inspiratory muscle strength, and a reduction in the perception of dyspnea and medication use. However, due to the limited number and discordant methods between studies more evidence is required to elucidate in asthmatics the efficacy of IMT on inspiratory muscle endurance, exercise capacity, asthma control, symptoms, quality of life, as well as adolescents with differing severities of asthma. Large randomized controlled trials would be a significant step forward in clarifying the effectiveness of IMT in asthmatics. While IMT may have favorable effects on inspiratory muscle strength, dyspnea and medication use, the current evidence that IMT is an effective treatment for asthma is inconclusive.