Scintigraphic imaging with radiolabeled blood elements has continued to be a useful diagnostic modality. The major trust of recent investigation has been in simplifying labeling techniques and developing new agents that will label blood elements selectively in vitro. The VI Symposium of the International Society of Radiolabeled Blood Elements was held in Barcelona (Spain) during November 23 to 27, 1992.The conference was sponsored by the NATO Scientific Affairs Division, the USA Department of Energy and the Spanish National Health Service. This monograph comprises articles that represent most of the 85 papers (70 oral and 15 posters) presented during the symposium. The meeting was attended by 110 investigators hailed from 21 countries. Although lllIn-oxine and 99mTc-HMPAO remain the choice agents for labeling blood components for routine applications, there was heavy emphasis on developing new labeling agents that will either simplify the in vitro labeling procedure, or, even better, will label blood components selectively in vivo, by injecting the radioactive agents directly into patients. The degree of success in imaging target lesions in humans by using these agents has been excellent.