The use of radioactive isotopes in the clarifaction of the metabolism of some elements play an important role in the life cycle. A systematic study is presented on the extraction of ionic iron from urine. As radioactive isotopes,59Fe was used to follow the extraction of the ionic forms in various extraction systems. For this study we used tributyl phosphate (TBP) as solvent. Such studies are useful to develop procedures for the separation and analysis of these elements such as for example in the study of the treatment of anaemia by the administration of their compounds in the human body.