Except in the case of exogenous allergic asthma, the therapy of chronic respiratory tract diseases must be predominantly symptomatic due to the polyaetiology and inhomogeneity of these diseases. Effective treatment of the main pathophysiological symptoms is important for the course and prognosis of the disease. These symptoms usually consist of hypersecretion, infection and bronchial obstruction. With the exception of "infective asthma", bronchial infections are not present at the onset of the illness. Such infections usually result as complications of a disease from which the patient is already suffering, and are essentially the consequence of disruption of the automatic clearance mechanism of the bronchial system and impairment of immunological defence against infection. The best form of therapy is that which is specifically directed at the individual bronchial infection for a period of two weeks. Permanent antibiotic prophylaxis is to a large extent obsolete today. In addition to treatment of bronchial infection, the removal of bronchial obstruction is also very important. Modern bronchospasmolytics are now among the most effective agents, provided the obstruction is actually "reversible". A low dose of oral corticosteroids - administered with caution - is justified should it not be possible to reduce pulmonary resistance to below the "dyspnoea threshold" of the patient.