Continuous treatment with antibiotics for 16 weeks was given to 10 patients with bronchiectasis who regularly produced purulent elastase positive secretions. Macroscopic clearance of secretions (from purulent to mucoid or mucopurulent) was achieved in all patients, and this was associated with a significant reduction in the average sputum elastase content by week 16 (p less than 0.001) when elastase was only detectable in three of the patients. Lung inflammation was also reduced as reflected in the sputum to serum albumin ratios. In addition patients noted a significant improvement in well being, and breathlessness as well as in sputum colour and volume and there was a significant improvement in peak expiratory flow. After cessation of treatment the time taken for the sputum to become purulent again ranged from 15 days to 10 months (median 2.5 months), which is longer than that seen previously following short courses of antibiotic treatment. Serum levels of the acute phase protein alpha 1 antichymotrypsin fell by week 16, although this failed to reach statistical significance. However, in eight patients where data were available the levels rose significantly after treatment had finished. The concentrations were consistently higher than those seen in healthy controls, and were also elevated in less severely affected patients suggesting that bronchiectasis is always associated with some systemic effect.