Radioactive drug development is a multi-disciplinary task, therefore, in a concerted effort, dedicated scientists and experts from different fields of specialisation have contributed to this book. It is presented in two sections. Section 1 contains basic principles and methods used for analysis, information on the chemistry of technetium and on radiopharmaceuticals labelled with technetium-99m, the characteristics of the 99 Mo/99mTc-generator, of 'kits' and formulations for in-vitro labelling, and special safety aspects for in-vivo labelling of blood cells. Section 2 contains monographs of 99mTc-radiopharmaceuticals used in nuclear medicine. Each monograph includes information on the chemistry, formulation, commercial products and trade names, factors affecting in-vivo performance, clinical information on pharmacokinetics, as well as details concerning the clinical application and the radiation dose to patients.