The fields of molecular biology, immunology and genetics have generated many important developments that advance the understanding of the induction and progression of oncological, cardiological and neurological diseases as well as the identification of disease-associated molecules and drugs that specifically target diseased cells during therapy. These insights have triggered the development of targeted radiopharmaceuticals which open up a new dimension of radiopharmaceutical sciences in nuclear medicine. Radiopharmaceuticals, also called radiotracers, are radiolabelled molecules, bearing a “radioactive lantern”, and used as molecular probes to address clinically relevant biological targets such as receptors, enzymes, transport systems and others. Positron emission tomography (PET) and single photon emission computed tomography (SPECT) realised in the en-vogue hybrid technologies PET/CT, SPECT/CT and PET/MRI represent the state-of-the-art diagnostic imaging technologies in nuclear medicine which are used to follow the trace of the administered radiopharmaceutical noninvasively thereby in vivo visualising and assessing biological processes at the subcellular and molecular level in a highly sensitive manner. In this connexion novel radiopharmaceuticals for the noninvasive molecular imaging of early disease states and monitoring of treatment responses in vivo by means of PET/CT, SPECT/CT and PET/MRI are indispensable prerequisites to further advance and strengthen the unique competence of radiopharmaceutical sciences. In the era of personalised medicine the diagnostic potential of radiopharmaceuticals is directly linked to a subsequent individual therapeutic approach called endoradiotherapy. Depending on the “radioactive lantern” (gamma or particle emitter) used for radiolabelling of the respective tracer molecule, the field of Radiopharmaceutical Chemistry can contribute to the set-up of an “in vivo theranostic” approach especially in tumour patients by offering tailor-made (radio)chemical entities labelled either with a diagnostic or a therapeutic radionuclide. [...]