Histamine is a natural amine present in many animal and human tissues. It was considered to be the mediator of immediate allergy. Histamine plays a role in various physiological processes, such as control of gastric acid secretion, neurotransmission and modulation of inflammatory and immunological reactions. This competitive enzyme immunoassay uses a prederivation (derivate reagent with a structure close to the spacer arm used for the immunogen preparation) of histamine that allows to enhance the sensitivity of the assay