In children, acute bacterial rhinosinusitis is a common infection and although rare, carries a potential for serious, life threatening complications. Bacterial rhinosinusitis usually follows a viral infection or allergic rhinitis. Early, effective antibacterial therapy is essential to shorten the duration of infection and illness, to diminish mucosal damage, and to prevent contiguous infectious involvement of the orbit or central nervous system. Because the signs and symptoms of acute bacterial rhinosinusitis are similar to those of viral upper respiratory tract infection, establishing an accurate diagnosis in children poses a clinical challenge. Infection with Streptococcus pneumoniae accounts for 30-66% of episodes of acute bacterial rhinosinusitis in children. Other important pathogens include Haemophilus influenzae (20-30%) and Moraxella catarrhalis (12-28%). In selecting initial antimicrobial therapy, priority should be given to drugs with activity against S. pneumoniae. The oral agents that currently offer the greatest activity against this pathogen include amoxicillin, amoxicillin-clavulanate, cefdinir, cefpodoxime proxetil, and cefuroxime axetil; all are considered appropriate for the initial treatment of acute bacterial rhinosinusitis in children. Amoxicillin is customarily used as first-line therapy for uncomplicated acute bacterial rhinosinusitis. For patients who are allergic to amoxicillin, second- or third-generation oral cephalosporins may be used as first-line therapy. Clarithromycin has been suggested as an alternative to amoxicillin or cephalosporins in beta-lactam allergic patients. Clindamycin may also be indicated as first-line treatment in patients who have culture-proven penicillin-resistant S. pneumoniae. If no clinical response occurs within 72 hours, the choice of a second-line antibiotic is governed by the drug's known antimicrobial efficacy, resistance patterns, dosing schedules, the potential for compliance, and knowledge of the patient's drug allergies. High-dose amoxicillin-clavulanate (90 mg/kg/d of the amoxicillin component) has been recommended for high-risk children (e.g. those in day care, and those who have recently received antibiotics) who show no improvement after treatment with the usual dose of amoxicillin (45 mg/kg/d). Broad-spectrum, third-generation oral cephalosporins, such as cefdinir, should be considered as second-line agents when standard therapy has failed or when patients show hypersensitivity to penicillin. Intramuscular ceftriaxone may be appropriate for patients who fail on a second course of antibiotic treatment.