A hypoallergenic diet in a proper sense does not exist. The prescription of a dietary treatment for allergic diseases or intolerance reactions is highly dependent on an exact allergologic diagnosis. An IgE-mediated allergy to food is treated by an elimination diet. In chronic disease, e.g. chronic urticaria or chronic abdominal symptoms, the relevance of specific IgE to food allergens can be proved by a diagnostic elimination diet, which is followed by oral provocation. In children at risk for atopic diseases (one or both parents or siblings with atopic diseases) a preventive diet during the first year of life is recommended. The cornerstones of such a diet are breast feeding during the first six months of life, late introduction of solid food and the avoidance of allergenic proteins such as cow's milk, eggs and fish during the first year of life. In intolerance reaction an additive free diet or a diet with low content of biogenic amines may be recommended. Patients with chronic urticaria or atopic dermatitis may suffer from an intolerance to histamine. A diet with a low content of biogenic amines may improve the condition of these patients.