The most frequent bacterial cause of pharyngitis/tonsillitis, a common infection in children, is group A beta-hemolytic streptococci. Prevention of acute rheumatic fever is the principal goal of treatment, although antibiotic therapy may also relieve the signs and symptoms of infection, shorten the infective period and prevent suppurative complications. Penicillin is the drug of choice. Alternatives are required, however, for patients allergic to penicillin and may be needed if the rate of bacteriologic failure with penicillin observed during the past decade continues. Erythromycin is generally effective in this infection, but its use, especially in children, is complicated by the need for multiple daily doses, a lengthy treatment period and a high rate of gastrointestinal side effects. The newer macrolides clarithromycin and azithromycin offer lower rates of gastrointestinal complaints and more convenient dosing. Clarithromycin is recommended for twice daily and azithromycin for once daily administration. Because of its prolonged tissue half-life, the recommended duration of azithromycin therapy is 5 days, compared with 10 days for penicillin, erythromycin and clarithromycin. Newer macrolides are rational alternatives to erythromycin for streptococcal pharyngitis/tonsillitis in penicillin-allergic patients.