Rare allergens in indoor environment are insufficiently recognized. The sources are diverse: they include animal, namely acaride, insect and mammalian allergens or vegetable allergens. The prevalence of sensitization to rare allergens depends on geographical and climatological characteristics, on people's habits and overall on dwelling specificities. Sensitizations to new rare allergens should be confirmed by documented clinical history, by immunological tests, and by the beneficial effects of avoidance. A review of rare and/or new allergens likely to be present in indoor environment is presented.