The hypothesis of this randomized placebo controlled trial is that targeted nebulized gentamicin to the airways will reduce bacterial burden and limit neutrophil airways inflammation. If given long term this will improve symptoms, pulmonary physiology, exercise capacity and health related quality of life with a reduction in exacerbation frequency and health care utilization.

Inclusion Criteria:

• Bronchiectasis confirmed by HRCT of the chest
• Clinically stable (not requiring antibiotics for at least 4 weeks preceding the study start date)
• Aged 18-70
• Chronic sputum production > 5 mls for the majority of days in 3 months before enrolment
• Chronically colonized (on at least 2 occasions in the preceding 12 months) whilst clinically stable
• At least two exacerbations in the past year
• Patients able to tolerate a nebulized gentamicin challenge
• FEV1 > 30% predicted
• Smoking < 20 pack year history and ex-smokers >1 year.

Exclusion Criteria:

• Cystic fibrosis
• Emphysema on HRCT chest
• Thoracic surgery within the past 1 year
• Allergic bronchopulmonary aspergillosis
• Poorly controlled asthma ( > 20% diurnal variation in peak expiratory flows despite treatment)
• Unstable angina or uncontrolled congestive cardiac failure
• Active malignancy
• Pregnancy or breast feeding
• Creatinine clearance < 30 mls/minute
• Vestibular instability
• Previous documented intolerance to aminoglycosides