Sinusitis is a common and significant acute and chronic clinical problem. Typically involving the paranasal sinuses, the inflammatory process may be induced by viruses, bacteria, or atopic conditions. ils a clinical process that: is frequently vague, acute bacterial sinusitis is diagnosed appropriately based on a set of typical sinusitis symptoms and the presence of symptoms for longer than is expected from a viral cause alone. Sinusitis may be acute (duration, <1 month); subacute (1 to 3 months); or chronic (>3 months). Amoxicillin is considered the treatment of choice in uncomplicated sinus infections because of its effectiveness in penetrating affected tissue and its low cost. When resistant organisms are likely to be the causative pathogen, reasonable second-line therapy includes amoxicillin/clavulanate, cefuroxime axetil, and some quinolones. Strategies that may increase the efficacy of management or prevention of disease resulting from less susceptible strains of Streptococcus pneumoniae include increasing the dose of amoxicillin and administering pneumococcal vaccines. A variety of adjunctive therapies, such as decongestants, corticosteroids, mucolytics, saline, and humidification, are available, hut there is scant evidence of their efficacy in reducing the severity, duration, or occurrence of bacterial sinusitis.