Viral upper respiratory infections occur frequently during childhood (6-8 per year) and are, for the most part, self-limited episodes that resolve spontaneously and do not require antibiotic therapy. Acute otitis media and acute bacterial sinusitis are frequent complications of viral upper respiratory infections that will benefit from treatment with antibiotics. Acute bacterial sinusitis is one of the most common diagnoses in ambulatory practice and, in all age groups, accounts for an estimated 25 million physician office visits annually. It is essential to distinguish between patients who are experiencing uncomplicated viral upper respiratory infections and acute bacterial sinusitis to avoid the excessive use of antibiotics for patients who will not benefit from them. This is especially important now because of the escalation of antibiotic resistance among the bacteria that commonly cause acute bacterial sinusitis, acute otitis media and pneumonia. Inappropriate use of antibiotics is a major contributor to the problem of antimicrobial resistance - a problem which dramatically increases both the cost and complexity of treatment.