This paper reviews activities in the field of radionuclide metrology applied to the life sciences between the years 2000 and 2005. The requirements for accuracy and consistency in making radioactivity measurements in radiation medicine, coupled with an increased awareness of the role of measurement standards in quality assurance programmes, has prompted a great deal of research in this area. During the past 5 years, particular emphasis has been on: (1) the development of primary standards for radionuclides, (2) development of secondary/transfer standards, (3) development of radionuclide standards for brachytherapy, and (4) inter-laboratory comparisons at the end-user level. Activities carried out by National Metrology Institutions in these areas are reviewed and a look at future trends is presented.