The clinical value of 13N-ammonia PET is reviewed by using previously published articles with significant evidence level. This meta-analysis indicated that due to excellent myocardial blood flow images, 13N-ammonia PET permits better diagnostic accuracy of ischemic heart disease and viability assessment than myocardial perfusion SPECT. Furthermore, quantitative assessment of myocardial blood flow (MBF) in absolute units can be performed using 13N-ammonia PET. MBF measurement is a useful tool to evaluate cardiac pathophysiology and monitor therapeutic effects of cardiac disease and cardiovascular risk factors.