Allergenicity to Brazil nut protein fractions and to a purified methionine‐rich 2S protein, considered to be similar to the allergens of other oilseeds, has been followed through IgG1and IgE synthesis after mouse subcutaneous immunization. The allergenic capacities of all protein fractions and of the 2S protein are not as prominent. Oral intake of Brazil nuts in several doses was also tested in mice and rats as a possible route of immunization, but instead of immunization, a systemic tolerance was induced. This state of immunological tolerance was more efficiently induced by a scheme of multiple feeding than by a single feeding.