Allergic rhinitis affects as many as 35 million people in the United States annually; of these, an estimated 19 million are employed adults. Overall, 10 to 30 percent of adults and up to 40 percent of children are affected, making it the sixth most common chronic illness in the United States. Approximately one-third to one-half of sufferers have seasonal rhinitis, with the remainder experiencing perennial disease or both seasonal and perennial forms of the disease. Other atopic conditions, such as atopic eczema, allergic conjunctivitis, and asthma, often co-occur. Estimates of the annual direct medical costs of allergic rhinitis in the US range from $1.16 billion to $4.5 billion, rising to $7.7 billion when indirect costs are included. These estimates, however, are based on information that predates the increased use of non-sedating antihistamines and nasal glucocorticoids. Recent prescription claims data show that approximately two-thirds of patients with allergic rhinitis receive treatment with one or more medications from these two drug classes, with expenditures exceeding $3.0 billion for prescription antihistamines alone. Rhinitis is typically classified etiologically into allergic and non-allergic causes. Non-allergic rhinitis is characterized by chronic nasal symptoms and the lack of identifiable allergic triggers. This report focuses on individuals with allergic rhinitis, including both seasonal and perennial allergic rhinitis. Seasonal allergic rhinitis is associated with sensitization to fungal, tree, grass, and weed pollens, and with symptoms that vary seasonally. Perennial allergic rhinitis is associated with sensitization to indoor allergens such as fungi, cockroaches, dust mites, and animal proteins (e.g., cat dander), and with year-round symptoms, with or without seasonal exacerbations. The physical symptoms of allergic rhinitis, such as sneezing, rhinorrhea, and nasal congestion, may interfere with one's ability to carry out daily activities. Rhinitis symptoms may be associated with headache, irritability, poor concentration, loss of sleep, and resulting fatigue. The functional impact of these symptoms ranges from mild to seriously debilitating effects on social, physical, and emotional functioning. Allergic rhinitis may interfere with cognitive tasks, may impair work performance, and may cause work absences. Because allergic rhinitis is so common in the population and allergens are ubiquitous, allergic rhinitis creates a significant burden in the workplace in terms of effects on work performance and health care costs. Although some occupational exposures to airborne allergens present in the workplace can cause occupational rhinitis, non-occupational allergic rhinitis represents a vastly greater burden in workplace settings overall. The emphasis on the working-age population raises unique issues, including the relationship between symptoms or functional status and work performance, the effects of allergic rhinitis and its treatments on costs and work performance, and variability in management approaches and patient outcomes among patients treated by generalist physicians, allergy specialists, and otolaryngologists.