[en] Measurement show that the body burden of ₁₃₇Cs in Lapps in Norway fell between 1965 and 1975 with an apparent half-life of 4-5 years. Since then the reduction has been considerable slower due to fallout from Chinese nuclear weapons testes. The content of ₁₃₇ Cs in reindeer meat follows the same pattern. Seasonal variations occur due to the migration of the reindeer between winter grazing on lichen with a high ₁₃₇Cs content and summer grazing on grass with a lower Cs content. For annual dose calculations it is found that whole-body measurements at the end of March or beginning of April give good values. The average body burden of ₁₃₇Cs in nomadic reindeer-herding Lapps corresponds to a whole-body irradiation of 15-20 mrem per year. Whole-body measurements made on employees at The Norwegian Radium Hospital indicate that radiation doses from body burden of ₁₃₇Cs in people in the Oslo area are far less than 1/10 of those of the Lapps. (RF)