Severe asthma is defined by persistent symptoms and frequent exacerbations despite intensive asthma therapy. The prevalence is estimated to be 5-10% of all asthmatics. Severe asthma is responsible for a major burden of illness including low quality of life and a disproportionate use of health-care resources. The clinical assessment of severe asthma must include verification of the correct diagnosis, adherence to medication, excluding differential diagnosis and identification and treatment of aggravating co-morbidities and trigger factors.