The use of inhaled aerosols allows selective treatment of the lungs directly by achieving high drug concentrations in the airway while reducing systemic adverse effects by minimizing systemic drug levels. Aerosol drug delivery is painless and often convenient, but the proliferation of inhaler devices has resulted in a confusing number of choices for clinicians who are selecting a delivery device for aerosol therapy. There are advantages and disadvantages associated with each device category. Several factors can guide clinicians to choose a device for a specific patient. This choice has to be tailored according to the patient's needs, situation and preference. Whatever the chosen inhaler, inhaler technique is the critical factor in the correct use of delivery devices and patient education has a key-role for improving technique and compliance.