Safety and Efficacy of Radiopharmaceuticals was established as a very important and comprehensive subject at the First Europe­ an Symposium on Radiopharmacy and Radiopharmaceuticals in Denmark in 1983. The interest in this subject has grown considerably since then due to the growing interest among national authorities to deal with radiopharmaceuticals. The introduction in recent years of nuclear medicine techniques based on radioactive labelled cells and on monoclonal antibodies has stressed the importance of a well functioning approval system for the clinical trial and use of new radiopharmaceuticals. The process of transferring the experience from the non radioactive drug field into the area of radiopharmaceuticals is still ongoing. International organisations such as the World Health Organisa­ tion is also including this into their quality assurance programme from both the radiopharmaceutical and the radiation hygiene point of view. In order to give an up-to date survey of these areas, experts were invited to prepare review papers under the following headings: Safety and Efficacy of Radiophar­ maceuticals with Emphasis on Biological Products, Radiophar­ macy/Radiation Hygiene, Legal Aspects of the Introduction of New Radiopharmaceuticals and some selected aspects of Good Radiopharmacy Practice.