Inhalation therapy is one of the main therapeutic modalities in modern pulmonology. It allows for the use of smaller daily doses of various medications which exhibit potent local therapeutic effects and low systemic action. Moreover, adverse effects, particularly the general (systemic) ones are minimal. The use of medical aerosols enables the treatment of not only diseases of the airways, but also makes it possible to deliver medicinal products that have a systemic effect (insulin, hormones, pain relievers or vaccines). The deposition of therapeutic molecules depends on a variety of factors (such as breath frequency, intensity of breathing or tidal volume). The greater the intensity of breathing (short, abrupt inspiration or a series of rapid shallow breaths), the greater the filtration ability of the upper airways (nasopharynx, larynx). These effects of the respiratory physiology should be always kept in mind since they are of key importance for a deposited (therapeutic) dose. The most common aerosol generators are pressurized metered dose inhalers and dry powder inhalers as well as nebulisers (jet, ultrasonic and MESH). All of these devices differ from one another in producing aerosol clouds (different particle diameters, different way of particle generation). That is why they cannot be used in all patients. Inhaler selection is one of the most important decisions in inhalation therapy. Its course and success are determined by multiple factors (patient-generated air flow, skill and ability to use aerosol generators). Prior to making a decision concerning treatment, an algorithm proposed by Laube et al. should be used since it makes inhaler selection considerably easier.