In the last 10-15 years, we have been dealing with a "second wave" of allergic disease outbreaks caused by food allergies. 60% of cases of food allergy in adults and children are associated with the co-occurrence of inhaled allergy. The structural similarity of proteins, even those of a different origin, is the main factor determining the occurrence of cross-reactions. The article reviews important clinical aspects of food allergy related to cross-reactivity syndromes.