A total of 51 technetium-99m (99mTc)-labelled autologous red cell (LRC) scans performed on 49 patients for the localization of obscure gastrointestinal bleeding over a 5-year period was reviewed. The sensitivity for LRC scanning was 72.7% with a positive predictive value of 84.2%. Forty patients underwent both LRC scanning and visceral angiography during the same admission; angiography had a sensitivity of 38.9% compared with 66.7% for LRC scanning and the positive predictive values were 77.8% and 85.7%, respectively. Overall, the site of bleeding was located in 22 (45%) of 49 patients, but LRC scanning alone was successful in identifying the lesion in 16 (33%) cases. In patients who continue to bleed to the point of requiring operation, a combination of scintigraphy and angiography will localize a source in 70% of patients.