Food allergy is an adverse food reaction as a result of immune mechanisms and is a key component in food safety issue. The prevalence of food allergy is known to be up to 6% of children and 3~4% of adults. A nationwide crosssectional questionnaire survey of Korean children in 1995 and 2000 revealed that there was a tendency of the prevalence of food allergy to increase. The most common allergen was egg, followed by milk, fish, and seafoods, such as crab, lobster and shellfish. However, this does not seem to reflect the true prevalence because diagnosis of food allergy was based on questionnaires but not food challenge tests but. Various symptoms are manifested in patients with food allergy depending on whether IgE- or non-IgE-mediated mechanisms are involved. The gold standard for diagnosing food allergy is double-blind placebo-controlled food challenge test (DBPCFC), which is both time- and effort-consuming. In clinical practice, a convincing history and positive specific IgE are very important for the diagnosis of IgE-mediated food allergy, and quantification of food-specific IgE is considered a useful test in some foods, such as egg, milk, peanut and fish in the pediatric population. The patients and their caregivers need to be educated about the way to avoid exposure to food allergens. However, recent progress in understanding of the immunopathogenesis of food allergy will lead to novel therapeutic approaches in the future.