^99mTc is the most widely used radionuclide in the nuclear medicine. Chemistry of the coordination compounds of Tc is given a permanent extraordinary attention in connection with the continued development of new radiopharmaceutical preparations for diagnostics. Stability, structure and lipophilicity of Tc complexes with ligands allowing for selective functional representation and organ distribution is studied with regard to the expected pharmacokinetic properties. Citrate ions, iminoacetate chelating groups, diphosphonate, mercaptoacetylglycinate, dimercaptosuccinate, hexamethylpropyleneaminoxime, methoxy-iso-butylnitrilo, ethylenedicysteine, and isocyanide ligands were studied in Tc complexes as ligands or complete chelating groups. The possible diagnostic applications of individual complexes is indicated. The survey of labelled Tc compounds for the verified diagnostic applications is given.