Fractional flow reserve (FFR) has been proposed as the gold standard to assess functional severity of coronary artery stenosis and to stratify which lesions should be subjected to intervention (percutaneous coronary intervention [PCI]). A systematic review was performed in MEDLINE and EMBASE including studies indexed until November 2013 that used FFR for deferral or performance of PCI. Outcomes of interest were death, acute myocardial infarction (AMI), and new revascularization (RV). Nineteen studies were included, totaling 3,097 patients (3,796 lesions). Mean follow-up was 21.2 months. In indirect comparisons, FFR-PCI and FFR-defer groups had similar death (2.2% vs 2.0%, respectively, p = 0.86) and AMI rates (1.9% vs 1.9%, respectively, p = 1.00). RV rates were higher in the FFR-PCI group (14.0% vs 4.4%, p = 0.002). Direct comparisons (2-arm trials) also showed no differences in death (odds ratio [OR] 1.86 [95% CI 0.81 to 4.27], I² = 11.5, p = 0.14) and AMI rates (OR 0.75 [95% CI 0.21 to 2.69], I² = 47.1, p = 0.66); RV rates were again higher in the FFR-PCI (OR 3.10 [95% CI 1.25 to 7.70], I² = 72.2, p = 0.015). Meta-regression suggests influence of male gender on RV rates (β = 0.058, p = 0.026). In conclusion, deferral of PCI based on FFR is a safe strategy. Considerable heterogeneity was observed, however.