[en] The first instrument to fulfill the purpose of a standard in Sweden was an ionization chamber designed by Rolf Sievert in 1925 (Sievert, 1925). It had been calibrated for the R-unit at the Physikalisch Technische Reichsanstalt in Germany. The roentgen unit was first internationally accepted in 1928, so radiation standards in Sweden have an old tradition. The first Swedish primary standard - a free air ionization chamber - was in use from 1930 (Thoreaus, 1932). Since then, a few more have been built and primary standards for X-rays were used towards the end of the 1960's. For higher photon energies, such as 1.25 MeV, a secondary standard, traceable to the National Bureau of Standards, USA, was established in 1956 (Thoreaus, 1962). During the 1970's, the laboratories were renovated and modern instrumentation and equipment were installed. Realizing the greatly improved qualities of modern ionization chambers and electrometers, as well as the amount of manpower necessary to keep primary standards of high quality, it was decided to abandon the primary standards and for the near future, rely on secondary exposure standards. This decision was made easier, as primary exposure standards had become available at the International Bureau of Weights and Measures (BIPM), Sevres. A Swedish Official Standards Laboratory Organization (SMO) was set up by the Swedish government in 1972. It consists of two kinds of laboratories, National Laboratories (riksmaetplatser, RMP) and Authorized Laboratories (auktoriserade maetplatser, AMP). Its headquarters is the Centre for Metrology (Maetcentrum). Since 1980, the National Institute of Radiation Protection is recognized as a National Laboratory for the quantities absorbed dose, dose equivalent, exposure and kerma