The use of positron emission tomography for clinical diagnostics has grown rapidly over the past 2 decades. This growth has mainly been due to advances in scanner technology, and particularly the introduction of the combined PET/CT scanner, and has been based almost exclusively on one PET radiopharmaceutical ([(18)F]fluorodeoxyglucose), which is broadly applicable to cancer patients. The availability of radiopharmaceuticals and the clinical diagnostic potential of PET has also supported the continued development of the scanner technology. Due to the efforts of many researchers worldwide in the field of radiopharmaceutical sciences, we are now seeing an increasing number of radiopharmaceuticals used for routine clinical diagnostic imaging. This article is intended as a short educational review, giving a brief overview of the design, preparation and use of PET radiopharmaceuticals, with some examples of highly clinically relevant PET tracers.