This review summarizes some of the developments of metal complexes and metal-complexbioconjugates for the diagnosis of disease states that have occurred over the past 10 years. The diagnostic imaging modalities discussed are gamma scintigraphy, positron emission tomography (PET) and magnetic resonance imaging (MRI). Metal complexes are utilized in all three imaging modalities to image a broad array of diseases, including heart disease, brain disorders and cancer. There are a wide variety of different radiometals that have been utilized in the synthesis of coordination compounds for gamma scintigraphy and PET, and these will be discussed individually. The field of metal-complex-bioconjugate chemistry is covered extensively, describing radiometals labeled to biomolecules such as receptor ligands for diseases such as neurological disorders and cancer. A section is devoted to the development of coordination compounds for MRI enhancement agents, and specifically details the agents that have been evaluated in vivo, both in animal models and in humans. Overall, the goal of this review is to demonstrate the significant progress made in the field of coordination chemistry as it applies to the development of diagnostic imaging agents.