Although positron emission tomography has remained until today poorly spread as an imaging technique, a significant development could be under way since (a) lower cost detectors are beginning to appear on the market, (b) the 2-hour half-life of fluor-18-labeled fluorodeoxyglucose (FDG) makes it transportable to centers located at distance of a regional cyclotron, and (c) there is a growing interest in the literature for the use of FDG in oncology. The aim of this review is to focus on the main indications of FDG in oncology, with an attempt to show its advantages as well as its drawbacks, in order to help those who could be considering to become involved into this fascinating field.