Food hypersensitivity includes adverse reactions to food which are most often mediated by IgE. Food allergy is the first atopic disease. Food-sensitized individuals can develop allergic reactions such as atopic dermatitis, urticaria, angioedema, rhinitis, asthma or digestive symptoms. Anaphylactic shock is the most severe reaction of immediate hypersensitivity. The prevalence of food allergy has drastically increased during the last years. Numerous food products can be involved, with special emphasis on masked allergens in processed foods. The diagnosis of food hypersensitivity is based on clinical history, analysis of patient's food intake, skin tests and placebo-controlled food challenge tests. Oral food-challenge tests allow a distinction between food sensitization and true food hypersensitivity. Treatment consists in avoidance of the offending food allergen associated with adjunctive therapy by antihistamines and disodium cromoglycate. The prescription of a first-aid kit is required in case of anaphylaxis. Specific immunotherapy seems to be an interesting therapeutic prospect. Prevention remains essential.