The pressurized metered dose inhalers and dry powder inhalers are the most widely used devices for inhalation therapy in asthma and chronic obstructive pulmonary disease; each of these devices have certain advantages and disadvantages that impact their use. Motivation from the virtues of these devices led to the development of breath-actuated or breath-activated metered dose inhalers. A history of the breath-actuated inhalers, the development and technical aspects, studies about the usability, inhalation technique and patient preference, lung deposition and impact on lung function are presented in this review article. This review presents the use of breath-actuated inhalers in asthma and chronic obstructive pulmonary disease and in children and elderly; and a brief economic evaluation aims to put the clinical efficacy and ease-of-use of the breath-actuated inhaler into perspective by understanding the long-term cost benefits associated with this device.