Molecular imaging represents an extremely important advancement in patient care and numerous agents have been developed and are being studied. Hundreds of molecular imaging agents currently exist for use in multiple modalities such as magnetic resonance imaging (MRI), computed tomography (CT), ultrasound, optical imaging, general nuclear medicine and positron emission tomography (PET). In PET, only a very small percentage of these agents are being used clinically in humans and more show promise for clinical use in the short-term future. The purpose of this paper is to present a brief overview of PET agents other than 18F-fluordeoxyglucose (FDG) that are either currently in clinical use in humans or in the authors' opinion are felt to show great promise for clinical use in the near future.