abstract Anthropogenic pollution and climate change are the two most significant threats for Arctic biodiversity and ecosystem functioning. Because of food chain biomagnification of lipophilic persistent organic pollutants (POPs), the polar bear is one of the species which have the highest levels of these harmful chemicals. Since POPs may have effects on hormone regulation and physiological homeostasis, reproduction and survival, POPs may adversely affect the plasticity of responses that polar bears have to environmental changes. Thus, in combination these two major anthropogenic factors may have a significant effect on Arctic ecosystem functions. The International Polar Year (IPY) project “BearHealth” aims at studying adverse health effects of POPs in polar bears, and the interacting effects of POPs and climate change on polar bears. In the circumpolar international project, several biomarker endpoints, such as immune, hormonal, vitamin, bone, and histological variables will be examined in relation to exposure to POPs and other emerging novel environmental pollutants. Analyses of chemicals and biomarkers will be conducted on archived material from biobanks, and on samples which will be sampled during the project period. In the Norwegian part of the project we will focus on health effects of POPs related to thyroid and reproductive hormone homeostasis and on vitamin A, E and D status, and on interactions between biomarkers, environmental pollutants and climate change variables, and on including new samples from polar bears from Svalbard and Barents Sea region. Efforts will also be made to obtain samples from the Russian Arctic. In cooperation with Danish researchers (which are the coordinators of the international BearHealth project), a study on POP related effects on bone density and structure will be performed on a large collection of polar bears skulls from the Norwegian Arctic and Greenland, and Russia if possible. The results from the Norwegian study will be integrated with the studies conducted by the other participating countries, and the project will end up in an integrated health risk assessment of the interactive effects of POPs and climate change in polar bears.