Background Bronchiectasis is a chronic inflammatory disease characterised by a recurrent cycle of respiratory bacterial infections associated with cough, sputum production and impaired quality of life. Antibiotics are the main therapeutic option for managing bronchiectasis exacerbations. Evidence suggests that inhaled antibiotics may be associated with more effective eradication of infective organisms and a lower risk of developing antibiotic resistance when compared with orally administered antibiotics. However, it is currently unclear whether antibiotics are more effective when administered orally or by inhalation. Objectives To determine the comparative efficacy and safety of oral versus inhaled antibiotics in the treatment of adults and children with bronchiectasis. Search methods We identified studies through searches of the Cochrane Airways Group's Specialised Register (CAGR), which is maintained by the Information Specialist for the group. The Register contains trial reports identified through systematic searches of bibliographic databases including the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, CINAHL, AMED, and PsycINFO, and handsearching of respiratory journals and meeting abstracts. We also searched ClinicalTrials.gov and the WHO trials portal. We searched all databases in March 2018 and imposed no restrictions on language of publication. Selection criteria We planned to include studies which compared oral antibiotics with inhaled antibiotics. We would have considered short-term use (less than four weeks) for treating acute exacerbations separately from longer-term use as a prophylactic (4 weeks or more). We would have considered both intraclass and interclass comparisons. We planned to exclude studies if the participants received continuous or high-dose antibiotics immediately before the start of the trial, or if they have received a diagnosis of cystic fibrosis (CF), sarcoidosis, active allergic bronchopulmonary aspergillosis or active non-tuberculous Mycobacterial infection. Data collection and analysis Two review authors independently applied study inclusion criteria to the searches and we planned for two authors to independently extract data, assess risk of bias and assess overall quality of the evidence using GRADE criteria. We also planned to obtain missing data from the authors where possible and to report results with 95% confidence intervals (CIs). Main results We identified 313 unique records through database searches and a further 21 records from trial registers. We excluded 307 on the basis of title and abstract alone and a further 27 after examining full-text reports. No studies were identified for inclusion in the review. Authors' conclusions There is currently no evidence indicating whether orally administered antibiotics are more beneficial compared to inhaled antibiotics. The recent ERS bronchiectasis guidelines provide a practical approach to the use of long-term antibiotics. New research is needed comparing inhaled versus oral antibiotic therapies for bronchiectasis patients with a history of frequent exacerbations, to establish which approach is the most effective in terms of exacerbation prevention, quality of life, treatment burden, and antibiotic resistance.