An open prospective, multicentre, comparative, randomized (2:1) study was conducted in 481 children diagnosed as having mild-to-moderate lower respiratory tract infections. The efficacy and safety of azithromycin suspension (10 mg/kg), dosed orally once daily for 3 days, was compared with that of co-amoxiclav (10 mg/kg in a 4:1 ratio), dosed orally three times daily for 5-10 days. The proportion of evaluable patients (n = 472) showing a cure or improvement was significantly higher in the azithromycin group (96.8%) than in the co-amoxiclav group (91%, P = 0.0199). There were six relapses in both groups, giving an overall response rate of 95% for azithromycin versus 87.1% for co-amoxiclav (P = 0.0025). Adverse events were reported in 10% of the patients treated with azithromycin, and 11.3% of co-amoxiclav patients. Reported and counted compliance was significantly better in the azithromycin group. A 3-day regimen of azithromycin was as effective and as safe as a 5-10 day regimen of co-amoxiclav in the treatment of respiratory tract infections in children, and compliance was improved.