Does subtraction scintigraphy improve the diagnostic utility of scintigraphic evaluation in acute lower gastrointestinal hemorrhage (LGIH)? Methods: This research was a retrospective clinical study using a repeat-measures design of randomized control and experimental groups. A single patient data set provided both the control group (conventional scintigraphy) and the experimental group (conventional and subtraction techniques). 49 raw 99mTc red blood cell studies were randomized and interpreted by four independent physicians as conventional scintigraphy data only (round one). The conventional scintigraphy studies were combined with subtraction images and randomized for re-interpretation (round two). Results: While there was a decrease in the mean, no statistically significant difference was noted between the mean time to bleed detection between interpretive round one and two (P = 0.524). The additional of subtraction scintigraphy to the interpretation process changed the outcome from ‘probably present’ to ‘absent’ for 14% of patients and from ‘equivocal’ to ‘absent’ in another 12% which had a marked effect on the false positive rate. The false positive rate decreased from 9.6% in round one to 3.6% in round two. ROC analysis showed that combining conventional scintigraphy with subtraction scintigraphy improves test performance. Conclusion: False positive studies can be reduced by utilizing subtraction scintigraphy in conjunction with conventional scintigraphy in the interpretive process.