The long-term monitoring of bio-accumulating contaminants in biota from terrestrial environments in Sweden as part of the Swedish National Environmental Monitoring Programme is based on analysis of organs and tissues of different animal species collected in certain pristine areas of the Swedish mainland (Odsjö and Olsson 1979 a,b). In the mountainous area of north-western Sweden, reindeer (Rangifer tarandus) is chosen as a representative indicator for the fauna living in that part of the country. Samples of reindeer have continuously been collected in three districts since the early 1980s. Later, the Declaration on the Protection of the Arctic environment established an Arctic Monitoring and Assessment Programme (AMAP) to monitor levels and assess effects of anthropogenic pollutants in components of the Arctic environment. The Programme recommends that collection of baseline data for heavy metals and radionuclides in caribou/reindeer should be mandatory for participating states due to the importance of that species in the diets of northern native people (AMAP 1993). The current material of reindeer from northern and central Lapland partly satisfies the Swedish association in the AMAP programme.The herbivorous reindeer spend the summer time in the westernmost part of the high mountain areas. Summer diets include grasses, sedges, twigs, leaves and mushrooms. During autumn they migrate eastwards to winter grounds in the central coniferous forest areas of the country, where they primarily feed on lichens, which are noted for their ability to accumulate nutrients and contaminants from the air. Winter diets also include sedges and twigs.The actual material of reindeer have earlier been utilised for analyses of e.g. radiocesium in a study of effects of the fallout of Cs-132 from the Chernobyl accident in 1986 (Forberg et al. 1992) and for studies of time trends of levels of HCHs and HCB (Odsjö et al. 1998).