There is considerable interest in 188Re due to its favorable properties as a therapeutic radionuclide. 188Re and 99mTc act as a matched pair because of their similar chemical properties, and therefore methods of labeling with 99mTc can be applied to the labeling with 188Re. With appropriately chosen agents as carriers of 188Re, the labeling can be readily carried out using 188ReO4- in the presence of a reducing agent. 188Re radio pharmaceuticals based on 99mTc complexes have been synthesized and are currently being studied for clinical use. Some of them are shown to be suitable for therapeutic use and promising for radiotherapy in nuclear medicine.