Radiolabelled human immunoglobulins have been available for 5 years. Within that time there have been many publications on the use of these agents labelled with both technetium-99m (99Tcm) and indium-111 (111In). The results of these data appear contradictory and only now do we understand both some of the mechanisms of radiolabelled immunoglobulins and some of their limitations. While 111In-polyclonal immunoglobulin seems to have a wide range of clinical applications in infection and inflammation, the more readily available 99Tcm-labelled product is best suited to the localization of peripheral bone and joint disease. The ease of producing these agents from commercially available immunoglobulins will ensure continued interest and research into these new tracers.