Studies of gastrointestinal bleeding, done with technetium-99m-labeled red blood cells were performed in 52 consecutive patients to determine whether cinematic acquisition and display localized sites of bleeding more accurately than did conventional static imaging. Computerized images were obtained for 15 seconds per image in 15-minute sets. Interpretations based on a cinematic display were compared with those based on standard 1-minute images obtained every 5 minutes. Pathologic confirmation of a site of bleeding was obtained in 21 patients. The cinematic display demonstrated bleeding not seen on static images and yielded either more accurate localization or increased sensitivity in eight of 21 patients (38%). Linear regression showed that the cinematic correlation (r = .98) to the actual site of bleeding was better than either of two readers' interpretations of the static display (r = .93, P less than .02; and r = .88, P less than .0004). The mean error for cinematic localization of bleeding (0.4 anatomic segments +/- 0.6 [standard deviation]) was less than that for the static interpretations (1.1 anatomic segments +/- 1.4) (P less than .01). It is concluded that computerized cinematic acquisition and display of scintigrams improves localization and detection of gastrointestinal bleeding.