The evaluation of adverse reactions to foods involving abnormal immune responses to food allergens remains an important part of the practice of allergy and immunology. Approximately 5% of children younger than 3 years and 1.5% of the general population experience food allergic disorders, indicating that about 4 million Americans suffer from food allergies. The evaluation of adverse reactions to foods depends on a careful clinical history, diagnostic studies including appropriate skin testing or in vitro testing with food extracts, and/or endoscopy and biopsy. The mainstay of therapy remains avoidance of incriminated foods and education to deal with inadvertent exposures. Experience over the past decade suggests that the ready availability and early introduction of highly allergenic foods (eg, peanuts and nuts) into the diet will only increase the number of individuals suffering from hypersensitivity reactions to foods. Research has focused on the identification and characterization of allergenic proteins and the development of new therapeutic strategies, eg, plasmid DNA vaccines, to treat these disorders.