The aim of this study was to investigate the long-term effectiveness and safety of inhaled antibiotic treatment in non-cystic fibrosis patients with bronchiectasis and chronic infection by Pseudomonas aeruginosa, after standard endovenous and oral therapy for long-term control of the infection had failed. After completing a 2-week endovenous antibiotic treatment to stabilize respiratory status, 17 patients were randomly allocated to a 12-month treatment either with inhaled ceftazidime and tobramycin (group A) or a symptomatic treatment (group B). One patient from group A abandoned inhaled treatment because of bronchospasm and another from group B died before the end of the study. The remaining 15 patients, seven from group A and eight from group B, completed the study. Both groups had similar previous characteristics. The number of admissions and days of admission (mean +/- SEM) of group A [0.6 (1.5) and 13.1 (34.8)] were lower than those of group B [2.5 (2.1) and 57.9 (41.8)] (P < 0.05). Forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1), PAO2 and PACO2 were similar in the two groups at the end of follow-up, showing a comparable decline in these parameters. There were no significant differences either in the use of oral antibiotics or in the frequency of emergence of antibiotic-resistant bacteria between groups. Microbiological studies suggested that several patients had different Pseudomonas aeruginosa strains. None of the patients presented impaired renal or auditory function at the end of the study. This study suggests that long-term inhaled antibiotic therapy may be safe and lessen disease severity in non-cystic fibrosis patients with bronchiectasis and chronic bronchial infection by Pseudomonas aeruginosa which do not respond satisfactorily to antibiotics administered via other routes.