Relatively sensitive kits--which are known for low tin content (HMPAO) or for a complicated chemical labelling procedure (MAG3)--were tested for their efficiency of labelling with eluates of different generators. The radiochemical purity of the labelling products was determined according to the manufacturer's instructions (HMPAO: Amersham Buchler, MAG3: Mallinckrodt Diagnostica) after adding the 99mTcO4- eluates from the different Tc-generators (Amersham Buchler, Mallinckrodt Diagnostica, CIS Biointernational). The radiochemical purity was determined by using radioanalytical methods such as high performance liquid chromatography, thin layer chromatography, paper chromatography and reversed phase chromatography. The quality of the three different generator eluates was sufficient for the labelling of HMPAO and MAG3. The small differences in quality did not limit the use in nuclear medical routine.