Food allergy in adults is mainly due to cross-reactivity between inhalative and food allergens. IgE antibodies are induced against aero-allergens, which recognize a structurally similar component in certain foods. Not all patients with such food allergies have clinical symptoms of pollinosis, although a sensitization to the inducing aero-allergens is always found. Dependent on the main allergen, namely Bet v 1 or Bet v 2, different symptoms can be observed. Bet v 1 mainly causes mild symptoms localized around the area of the oropharynx (oral allergy syndrome). It is mainly caused by apples, cherries, peaches and plums, but can also be observed with other allergens which cause generalized symptoms. Sensitization to Bet v 2 is commonly associated with more generalized symptoms, in particular urticaria and angioedema (mugwort/celery syndrome). Recently, new cross-reactivities have been detected based on latex sensitivity or housedust mite sensitivity. Latex allergy can cause food allergy to avocado, banana and chestnut, housedust mite allergens to crustacea and snails. Knowledge of these cross-reactivities is important for the clinician, since the majority of food allergies are caused by such cross-reactive IgE-antibodies. Further characterization of these allergens may open up ways of inducing tolerance to these substances.