Background The assessment of moderate coronary artery disease (CAD) has been heavily decided on the basis of angiographic appearance. Fractional Flow Reserve (FFR) is an established procedure in deciding management of moderate CAD. Purpose In this study, we have assessed the costs of FFR use in guiding coronary intervention; in terms of intervention rates and hospital stay in days. We also measured the rates of readmission with chest pain and revascularisation. We calculated the projected costs if the operators adopted 100% and 50% intervention strategies, and then calculated the potential added or saved costs for both strategies. We also calculated the saved costs depending on whether the operator performed adhoc FFR, staged after acute coronary syndrome or staged after outpatient angiogram. Methods We retrospective reviewed all FFR procedures done in our centre between 28/11/2012 to 14/12/2014. The rates of readmission with chest pain and revascularisation were calculated for the intervention group and medical therapy group. We measured the numbers of FFR positive procedures (less than 0.8) and subsequent PCI or CABG and hospital stay. This was compared to strategies of PCI to all comers (100%) or 50% of the cohort. We also stratified the differences in the costs according to the type of FFR to (1) Patients received adhoc FFR* (2) Staged FFR after ACS (3) Staged FFR after outpatient angiogram. The cost of 1 FFR procedure is 560 euro, PCI = 750 euro, CCU 1 day stay is 1000 euro, CABG 5000 euro. *Adhoc FFR; describes the practice of proceeding to FFR immediately after diagnostic coronary angiogram during the same session. This may be followed with adhoc PCI if the patient is already on dual antiplatelet therapy or followed by staged FFR at a later date. Results Total of 108 FFR procedures were performed in 105 patients in our centre. 1 procedure failed. Among the remaining 107 procedures performed, FFR measurement was done on 120 lesions. The mean age was 63.8 years, 29% were females. Indications of the 107 procedures were 31 ACS, 18 previous ACS for stage FFR and 58 with stable angina. FFR artery: LAD = 65 patients, RCA = 28, LCX = 16, LMS = 5, OM = 5 and diagonal = 1. Median follow up period = 458 days, range (53–785). Mean 439, 95% CI (397–481). Clinical outcomes 24 Patients (27 lesions) had positive FFR value. 21 patients (23 Lesions) received PCI with total of 35 stents. 2 patients (3 lesions) received CABG. 1 patient received medical treatment as was diagnosed with malignancy afterward. Readmission with chest pain = 12 out of 104 patients. (4/24 = 16% FFR positive), (8/80 = 10% FFR negative) P = 0.12. Revascularisation rate = 2 (both FFR negative) P value 0.45. Costs If 100% of patients underwent PCI, 107 FFR procedures (60,000 euro) would have saved 85 PCI, 3 CABG and 56.5 days in CCU. (61,830 euro or 578 euro per procedure). If 50% of patients underwent PCI, 107 FFR procedures would have saved 33 PCI, 2 CABG and 28.5 days in CCU. Total saved 3000 euro (29 euro per procedure). 54 adhoc FFR procedures saved 42 PCI, 3 CABG and 39 days in CCU (986, 2 euro /procedure). 35 elective FFR post elective angiogram saved 30 PCI, 14.5 days in CCU (497 euro /procedure). 18 staged FFR post ACS saved 11 PCI procedures, 12 days in CCU (565 euro /procedure). Conclusion With similar rates of readmission and revascularisation, FFR guided intervention avoided significant number of PCI and reduced hospital stay compared to strategies with 50 or 100% intervention rates. The practice of adhoc FFR seems to offer the best cost saving strategy.