Infection imaging became widespread in 1971 with the release of ⁶⁷Ga citrate. Multiphase skeletal scintigraphy and radiolabeled white blood cells (WBCs) have since become the most widespread clinically used agents for the imaging of infection. A wide variety of other radiolabeled probes are under investigation, based on antibodies, cytokines, assorted proteins and other molecules, alone or in various combinations. However, these latter agents, with a few exceptions, are not routinely used clinically. Radiolabeled ciprofloxacin represents the first attempt to develop an infection-specific imaging agent (most infection-imaging probes localized nonspecifically to inflammation as well), but it has not proven superior to radiolabeled WBCs or ¹⁸F-fluoro-deoxy-glucose (FDG) PET. Because of the ability to combine exquisite anatomic detail with focal uptake of ¹⁸F-FDG, PET–computed tomography has achieved great success in the detection and localization of infection, including in clinically adverse conditions. Despite these advances, at this time an infection-specific imaging agent does not exist.