A total of 371 children, aged 6 months to 12 years, with acute otitis media, acute sinusitis, streptococcal tonsillitis/pharyngitis, or pneumonia were included in an open, multicenter study. Among them, 192 children were randomized to receive azithromycin for 3 days (10 mg/kg daily), and 179 for 5 days (10 mg/kg on day 1 and 5 mg/kg on days 2-5). The overall clinical cure rate was 95.7% and 96.1%, and bacteriological eradication rate 90.1% and 94.2% in the 3-day and 5-day groups, respectively. Side effects, mostly mild gastrointestinal disturbances, were observed in 5.3% of children from the 3-day, and 6.7% from the 5-day group. Only in one child (0.3%) was therapy discontinued due to vomiting. The results of this study demonstrate that 3-day and 5-day azithromycin courses have comparable efficacy and tolerability in children with respiratory infections.