This thesis gives an overview of metal ion interactions with different kinds of biomolecules (proteins, enzymes, nucleic acids etc.). In general, the interactions depend on the biological species and their properties, as well as on the electron transitions inside the atom, which affects the chemical activity and the ability of the element to react with the target tissue – ligands. More detailed consideration is given to the essential elements (e.g. Cu, Se, Fe, Zn), due to the fact that their absence in the organism leads to various disfunctions, including death, while, on the other hand, in abundance, these elements might have a toxic effect. Biological ligands most commonly form bonds with metal ions via nitrogen, oxygen or sulphor atoms, and coordinate the metal center in a strictly specific way. The role of the biological ligand in the organism is most frequently taken by water, inorganic anions (\(^{CL-} \),\(^{{CO_{3}}^{2-}} \), \(^{^{{PO_{4}}^{3-}}}\)) , various proteins, porphyrins and nucleic acids. Other significant biological ligands are various coenzymes, vitamins and many other organic molecules which partake in the metabolism (e.g. riboflavin, nicotinamide, biotine).