Allergic Rhinitis (AR) is caused by IgE-mediated inflammation and results in nasal symptoms including sneezing, rhinorrhea, nasal itching, and nasal obstruction. Why genetic predispositions and environmental influences lead to the development of AR in some populations but not others is not well understood. AR is a heterogeneous disease with epidemiology and severity notable for substantial variability. The diagnosis of AR is complicated by non-specific symptoms and physical findings while allergy testing is known to have a high false positive rate. Moderate to severe AR can have a significant negative impact on an individual’s health measures including decreased quality of life, reduced work productivity, poor school performance, and sleep disturbance. The direct and indirect costs of AR are substantial despite many with mild symptoms. While AR is associated with other allergic conditions, the relationship is not consistently strong in all studies. Most of the epidemiologic information is from children and young adults in whom AR is most common.