Nebulized amoxicillin (500 mg twice a day) was given for four months to six patients with bronchiectasis. The patients had continually produced purulent secretions, which had failed to clear (purulent to mucoid) when amoxicillin was given orally (3 gm twice a day). All patients found the nebulization technique acceptable, and no acute effect on lung function was seen. There were significant reductions in sputum purulence (P less than 0.025) and volume (P less than 0.05) and a mean (+/- SD) increase in peak expired flow rate (P less than 0.05) from 230.5 +/- 79.2 L/min to 255 +/- 90.1 L/min. These improvements occurred despite the fact that apparently resistant bacteria were cultured. No adverse effects were noted. The response to nebulized amoxicillin after failure with the same drug given orally suggests that local concentrations of antibiotic in the lungs of these patients is important.