Summary: Inhaled therapy is the cornerstone of pharmacological treatment in asthma and chronic obstructive pulmonary disease (COPD). International and Polish guidelines on asthma or COPD management emphasize the significance of proper inhalation technique, as it determines both efficacy and safety of inhaled medicines. Despite awareness of the problem, inhaler mishandling is still a common problem that affects many patients with asthma and COPD. In this review, we discuss types of inhalers, the most common inhaling mistakes and the effects of inhaling mishandling on the course of asthma and COPD.