This review addresses the diagnosis and treatment of acute and chronic rhinosinusitis. Antimicrobial and adjuvant therapies, including topical treatments, are discussed. Surgical intervention is included in the treatment options. Clinical characteristics of rhinosinusitis are presented with an emphasis on history and physical examination. The use of imaging is described with regard to the indications for imaging and selection of imaging modalities. Complications of rhinosinusitis, with management recommendations based on recent data, are described. The evaluation and management of patients with cystic fibrosis and allergic fungal sinusitis is part of the discussion of less common scenarios of patients with sinus disease.