99mTc RBC scintigraphy offers a powerful detection and localisation tool that may be confounded by false positive and false negative findings. Subtraction scintigraphy has been utilised in the evaluation of acute LGIH to reduce the impact of interpretive confounders. The aim of this investigation was to evaluate the cost effectiveness of the addition of subtraction scintigraphy in the evaluation of the acute LGIH patient. Methods: The clinical phase of the research was a retrospective clinical study using a repeat-measures design of randomised control and experimental groups. A total of 49 patients studies were included in the sample. Studies were randomised and interpreted by four independent physicians. Decision tree analysis was utilised to model direct costs and the potential risks of procedures for two diagnostic strategies in the acute LGIH patient; conventional scintigraphy alone and conventional scintigraphy combined with subtraction scintigraphy. The transition probabilities for scintigraphy were then based on the clinical results of this investigation. All other transition probabilities were derived from previously cited data. Results: Combining subtraction methods with conventional scintigraphy reduced the overall costs of procedures in the acute LGIH patient by $74 per patient and reduced deaths by 17.6% and complications by 15.7%. For conventional scintigraphy alone, 8.8% of patients presenting with acute LGIH for scintigraphy will undergo unnecessary angiograms and 2.8% will have unnecessary surgery. These figures were reduced to just 5.4% and 1.8% respectively with the addition of subtraction scintigraphy. Conclusion: Utilising subtraction scintigraphy as an adjunct to conventional scintigraphy in the acute LGIH patient may extend both cost and outcome benefits.