Revascularization of coronary artery stenosis should be based on objective evidence of ischemia. Fractional flow reserve (FFR) is an invasive physiologic index that can be easily measured in the cardiac catheterization laboratory to assess the functional significance of coronary stenosis. FFR-guided revascularization strategy has been proven to be better than angiography-guided strategy in patients with coronary artery disease. Recent development of more convenient ways to induce hyperemia will reduce the barrier to measuring FFR and further expand its clinical applicability. Invasive physiologic indices without hyperemia are also under active investigation. Moreover, a novel noninvasive FFR measurement based on coronary CT angiography and computational fluid dynamics has been developed and will soon be incorporated into clinical practice. Given the rapid adoption of invasive and noninvasive physiologic indices in daily practice, a review of the current status of FFR and future perspectives is presented.