18-F-fluoro-D-deoxyglucose positron emission tomography (FDG PET) has become an established imaging tool in clinical oncology, cardiology and neurology and is now entering the field of clinical infectious diseases. The purpose of this article is to review the currently available, albeit limited, literature on FDG PET in the diagnosis of various infections and fever of unknown origin. Those indications for which FDG PET offers added value over more available techniques like labelled leucocyte scanning, gallium scanning and magnetic resonance imaging are especially highlighted. FDG PET seems to have an incremental value in the assessment of chronic osteomyelitis, especially in the axial skeleton, as well as in the diagnostic workup of fever of unknown origin and HIV complications. Cost-effectiveness studies are needed to define its place in the current diagnostic strategies of these pathologies.