Immunoglobulin E (IgE) serves as an important link between innate and adaptive immunity through its ability to bind high affinity receptors on mast cells and basophils. Large differences in IgE levels may here affect this important link, and IgE levels in natural non-domestic animal populations may therefore be very informative concerning the levels of IgE that this system have been balanced against during recent mammalian evolution. However, very few such studies have been performed. Here, we present an analysis of total IgE levels in 65 Scandinavian wolves: 57 free living (wild), and 8 wolves in captivity (Zoo). The 57 wild wolves correspond to approximately 30% of the entire wolf population in Sweden and Norway and thus represent a large fraction of the entire population, making this a unique sample from a wild canine population. The median IgE level in these wolves was 67 microg/ml, which is approximately twice the level seen in domestic dogs and more than 100 times the levels in non-atopic humans. The collected information from domestic and wild populations now indicate that the very low IgE levels observed in man and laboratory rodents are most likely an effect of a life in a relatively parasite free environment, and that total IgE levels under maximally stimulatory (normal) conditions may reach 100-200 microg/ml.