Infants and young children, especially those in day care, are at risk for recurrent or persistent acute otitis media (AOM). There are no data on oral alternatives to high-dose amoxicillin-clavulanate for treating AOM in these high-risk patients. In this double-blind, double-dummy multicenter clinical trial, we compared a novel, high-dose azithromycin regimen with high-dose amoxicillin-clavulanate for treatment of children with recurrent or persistent AOM. Three hundred four children were randomized; 300 received either high-dose azithromycin (20 mg/kg of body weight once a day for 3 days) or high-dose amoxicillin-clavulanate (90 mg/kg divided twice a day for 10 days). Tympanocentesis was performed at baseline; clinical response was assessed at day 12 to 16 and day 28 to 32. Two-thirds of patients were aged < or =2 years. A history of recurrent, persistent, or recurrent plus persistent AOM was noted in 67, 18, and 14% of patients, respectively. Pathogens were isolated from 163 of 296 intent-to-treat patients (55%). At day 12 to 16, clinical success rates for azithromycin and amoxicillin-clavulanate were comparable for all patients (86 versus 84%, respectively) and for children aged < or =2 years (85 versus 79%, respectively). At day 28 to 32, clinical success rates for azithromycin were superior to those for amoxicillin-clavulanate for all patients (72 versus 61%, respectively; P = 0.047) and for those aged < or =2 years (68 versus 51%, respectively; P = 0.017). Per-pathogen clinical efficacy against Streptococcus pneumoniae and Haemophilus influenzae was comparable between the two regimens. The rates of treatment-related adverse events for azithromycin and amoxicillin-clavulanate were 32 and 42%, respectively (P = 0.095). Corresponding compliance rates were 99 and 93%, respectively (P = 0.018). These data demonstrate the efficacy and safety of high-dose azithromycin for treating recurrent or persistent AOM.