Positron emission tomography (PET) myocardial perfusion imaging has higher spatial resolution than conventional single photon emission computed tomography (SPECT) imaging and allows accurate and reproducible quantification of myocardial blood flow (MBF). In this article, we describe the role of PET myocardial perfusion imaging in clinical decision making in children with suspected coronary abnormalities. We performed a PET myocardial perfusion study using N-13 ammonia in 10 children (median age, 14 years; range, 1-17 years). The indications included exercise-induced chest pain and ST segment changes during exercise testing, coronary artery ectasia, hypertrophic cardiomyopathy with myocardial bridging of the left anterior descending coronary artery, and suspected left coronary stenosis in an infant with William's syndrome. MBF was assessed at baseline and during adenosine hyperemia in all 10 patients and postexercise in 8 patients. Myocardial perfusion was homogeneous at baseline in all 10 patients, during adenosine perfusion in 9 of 10 patients, and postexercise in all 8 patients. Three patients with homogeneous rest and stress perfusion had impaired myocardial flow reserve. The infant with William's syndrome developed a large, reversible perfusion defect in the left coronary territory during adenosine stress and underwent surgical repair. Myocardial flow reserve findings were valuable for clinical decision making in individual patients. We conclude that MBF quantification with N-13 ammonia and PET provides supplemental perfusion information and is helpful in clinical decision making in children with suspected coronary abnormalities.