The term "food allergy" is widely misused for all sorts of symptoms and diseases caused by food. Food allergy (FA) is an adverse reaction to food (food hypersensitivity) occurring in susceptible individuals, which is mediated by a classical immune mechanism specific for the food itself. The best established mechanism in FA is due to the presence of IgE antibodies against the offending food. Food intolerance (FI) are all non-immune-mediated adverse reactions to food. The subgroups of FI are enzymatic (e.g. lactose intolerance due to lactase deficiency), pharmacological (reactions against biogenic amines, histamine intolerance), and undefined food intolerance (e.g. against some food additives). The diagnosis of an IgE-mediated FA is made by a carefully taken case history, supported by the demonstration of an IgE sensitization either by skin prick tests or by in vitro tests, and confirmed by positive oral provocation. For scientific purposes the only accepted test for the confirmation of FA/FI is a properly performed double-blind, placebo-controlled food challenge (DBPCFC). A panel of recombinant allergens, produced as single allergenic molecules, may in future improve the diagnosis of IgE-mediated FA. Due to a lack of causal treatment possibilities, the elimination of the culprit "food allergen" from the diet is the only therapeutic option for patients with real food allergy.