In the first part of our editorial we reviewed the possible factors responsible for mucus hypersecretion in acute and chronic pulmonary diseases. The present paper presents the results of studies proving, that mucolytics are useful in adjunctive therapy of respiratory tract disorders. Mucolytic agents such as Ambroxol and N-acetylcysteine are able to alter the secretion of mucus and its physical properties which results in improvement of mucociliary clearance. Current evidence indicate, that these drugs are effective, especially in chronic obstructive pulmonary disease, asthma and acute bronchitis. They produce a modest improvement in symptom control and lung function. It has been demonstrated that there is a synergism between mucolytics and antibiotics in the treatment of exacerbation of chronic bronchitis. Moreover, they act as scavengers of reactive oxygen species. Ambroxol is able to inhibit mediator release involved in the pathogenesis of allergic inflammation. As mucolytics are cheap and well-tolerated they are beneficial in the therapy of patients suffering from respiratory tract disorders.