In 1960 Caesium-137 activity from atmospheric nuclear weapons test was dis-covered in measurements at the whole body gamma-ray counting laboratory inLund. This event initiated measurements of the Swedish Sami population, and inproducts from reindeer that bite lichens in the Swedish mountains. A semi-portable whole-body counter designed with a detection limit for 137 Cs at high radiation background areas which was good enough for measuring people with high body concentration of 137 Cs. The 137 Cs activity concentration in Sami people increased during 1963 -1965 from 300 to 600 Bq/kg body weight. Some individual males had values above 1000 Bq/kg. The catastrophic nuclear accident on the 25 – 26 April 1986 at the Chernobyl Nuclear Power Plant caused a massive release of fission- and neutron-activation products to the atmosphere. Already the following day the atmospheric plume of released radioactivity reached Sweden and was deposited over the central part of Sweden also in Sami populated reindeer raising districts. During 1991 and 1992 whole-body content of 137 Cs was measured in the Sami population of northern Sweden and similar levels were found as during 1963 –1965. These levels are about twice those estimated in people living in the Chernobyl contaminated area
