Acute otitis media (AOM) is the most frequent bacterial disease and leading cause of antibacterial prescriptions in infants and children. Although AOM resolves spontaneously in most patients, antibacterial treatment is believed to be indicated in most industrial countries, particularly for infants, to prevent severe complications and relieve symptoms more rapidly. The classical duration of oral antibacterial therapy has been 10 days. During the last decade, the efficacy of shortened course antibacterial therapy has been demonstrated in many trials. Advantages of shorter treatment periods include less expense, better compliance, and potentially less impact on the commensal flora. However, short course antibacterial therapy may not be appropriate for children <2 years of age, particularly those attending daycare centers, those with otorrhea or a recent episode (<1 month), and otitis-prone children. Reasons for a poorer efficacy in these groups of children are still not completely understood.