The mechanism by which macrolide antibiotics have immune modifying effects independent from its antibacterial activity has not been well established. In the present work, we will analyze the effect of long-term treatment with azithromycin (AZ) on airway oxidative stress markers in exhaled breath condensate of adult patients with stable non-CF bronchiectasis. Patients will be randomized in an open label model to receive AZ 250 mg three times per week during three months or nothing.Dyspnea (Borg scale), exacerbations (Nº) in the last three months, sputum volume (cc), sputum colour (15-point scale), and health related quality of life (Questionnaire St.George) will be measured in both groups before and after treatment. Lung function, sputum culture, CT scan (Bhalla score) and inflammatory markers in blood (ESR, PCR),exhaled air (Nitric Oxide,) and exhaled condensed air (pH, nitrites, isoprostane) will be assessed before and after treatment. Relationships between clinical and inflammatory markers will be studied