A prospective randomized study was performed in order to compare the efficacy of oral levofloxacin, a new S- isomer of ofloxacin, with intravenous ceftazidime in the empirical treatment of acute exacerbations of bronchiectasis. Consecutive patients with acute exacerbation of bronchiectasis were recruited at a tertiary referral centre and were randomized to receive 10 days' treatment with either oral levofloxacin (300 mg b..d.) or ceftazidime (1 g i.v.t.d.). Body temperature, cough score, dyspnoea score, sputum purulence and volume and white blood cell and neutrophil count were assessed on day 1 and day 10. Thirty-five patients (mean age 61 yrs, 15 males) completed the study; 17 of these were in the levofloxacin group. There was no significant difference in the distribution of sputum pathogens or clinical parameters between the two groups at entry to and completion of the study. Both groups of patients showed significant improvement in 24-h sputum volume, sputum purulence score, cough score and dyspnoea score (p<0.001) but there was no significant difference between these two groups at entry to or on completion of the study (p>0.05). The results of this study suggest that oral administration of levofloxacin is as effective as parenteral ceftazidime in the empirical treatment of exacerbations in bronchiectasis.