AIM: To determine the role of scintigraphy in patients with gastrointestinal (GI) bleeding of unknown localisation. METHODS: We performed retrospective analyses on 92 patients receiving scintigraphies from 1993 to 2000 in the University of Regensburg hospital, which were done for localisation of GI bleeding as a diagnostic step after an unsuccessful endoscopy. In addition to the scintigraphies, further diagnostic steps such as endoscopy, angiography or operations were performed. In some of the scintigraphies with negative results, a provocation test for bleeding with heparinisation was carried out. RESULTS: 73% of all scintigraphies showed a positive result. In 4.5% of the positive results, the source was located in the stomach, in 37% the source was the small bowel, in 25% the source was the right colon, in 4.5% the source was the left colon, and in 20% no clear localisation was possible. Only 4% of all scintigraphies were false positive. A reliablepositive scintigraphy was independent of the age of the examined patient. A provocation test for bleeding with heparin resulted in an additional 46% of positive scintigraphies with a reliable localisation in primary negative scintigraphies. CONCLUSION: Our results show that scintigraphy and scintigraphy with heparin provocation tests are reliable procedures. They enable a reliable localisation in about half of the obscure GI-bleeding cases. Scintigraphy is superior to angiography in locating a bleeding. It is shown that even in the age of video capsule endoscopy and double-balloon enteroscopy, scintigraphy provides a reliable and directed localization of GI bleeding and offers carefully targeted guidance for other procedures. AIM: To determine the role of scintigraphy in patients with gastrointestinal (GI) bleeding of unknown localization. METHODS: We performed retrospective analyzes on 92 patients receiving scintigraphies from 1993 to 2000 in the University of Regensburg hospital, which were done for localization of GI bleeding In addition to the scintigraphies, further diagnostic steps such as endoscopy, angiography or operations were performed. In some to the scintigraphies with negative results, a provocation test for bleeding with heparinisation was carried out. RESULTS: In 4.5% of the positive results, the source was located in the stomach, in 37% the source was the small bowel, in 25% the source was the right colon, in 4.5% the source was the left colon, and in 20% no clear localisation was possible. Only 4% of all scintigraphies were false positive. A reliablepositive scintigraphy was independen t of the age of the examined patient. A provocation test for bleeding with heparin resulted in an additional 46% of positive scintigraphies with a reliable localisation in primary negative scintigraphies. CONCLUSION: Our results show that scintigraphy and scintigraphy with heparin provocation tests are reliable procedures They enable a reliable localisation in about half of the obscure GI-bleeding cases. It is shown in even the age of video capsule endoscopy and double-balloon enteroscopy, scintigraphy provides a reliable and directed localization of GI bleeding and offers carefully targeted guidance for other procedures.