The principles governing metal-ligand complex stability and specificity depend on the properties of both the metal and the chelating agent. The exploration of coordination chemistry offers the real prospects of providing new understanding of intractable diseases and of devising novel therapeutics and diagnosis agents. Refinement in the approach to chelator design has come with a more subtle understanding of binding kinetics, catalytic mechanisms and donor interactions. Ligands that effectively bind metal ions and also include specific features to enhance targeting, reporting, and overall efficacy are driving innovation in areas of disease, diagnosis and therapy. In this contribution the topics of bioinorganic medicinal chemistry, chelating agents in the treatment of metallic ion overload in the body, and expanding the notion of chelating agent in medicine are successively dealt with, paying then attention to platinum, gold, iron, copper and aluminium ion metal complexes having medicinal interest. A tabular summary containing selected applications of ligands and complexes of therapeutic interest is also shown to including the most relevant and current bibliography. A number of papers concerning miscellaneous topics based on selected key words are also tabulated. Metal chelation principles offer wide new opportunities in the drug design field in addition to the classical answer of metal sequestration or elimination.