PURPOSE: Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death in the world and it is characterized by airflow limitation. Pathophysiologically COPD involves many components including mucus hypersecretion, oxidative stress and inflammation, contributing to corticosteroid resistance. Carbocysteine lysine salt (CLS) is a mucoactive drug with mucoregulatory, anti-inflammatory, antioxidative effects and could also restore steroid sensitivity, offering promise for treatment. Assessment of COPD is also based on risk of exacerbation. The results of PEACE study showed that long-term use of carbocysteine lead to a 25% reduction of exacerbations in GOLD II-IV, with significant benefit in patients with > 1 exacerbation. However, only 17% of PEACE study patients received background therapy including inhaled steroids (IS). The aim of this observational prospective real life clinical trial was to evaluate the correlation between frequency of exacerbations in patients that experienced more than 2 episodes during the study and treatment adopted, included CLS with or without IS.