Fractional flow reserve (FFR) at the time of invasive coronary angiography is the current gold standard for determination of ischemia. Coronary CT angiography (coronary CTA) has emerged as an effective noninvasive method for direct visualization of coronary artery disease. However, severe stenosis by coronary CTA are only modestly predictive of ischemia. Recent technological innovations enable non-invasive calculation of FFR from CT. FFRCT is superior to anatomic assessment of stenoses in coronary CTA for the diagnosis of ischemia-causing lesions on both a per-patient and a per-vessel basis. FFRCT improves the diagnostic accuracy mostly by reducing the false positive rate of stenosis assessment alone. Furthermore, in patients where CT demonstrates an intermediate stenosis, FFRCT demonstrates significantly higher diagnostic performance than anatomic assessment alone.