Acute myocardial infarction (AMI) is extremely rare in children, and unlike the adult disease, the etiology of the infarction is rarely due to atherosclerotic coronary disease. This unique reported case involved a 15-year-old boy with severe chest pain who presented with an ST-segment-elevation myocardial infarction secondary to in situ thrombus formation in the left anterior descending (LAD) coronary artery. The initial electrocardiogram (ECG) had a Q-wave pattern in V6 and ST depression in the inferior leads with ST-segment elevation in reciprocal leads. The cardiac enzymes and routine labs showed evidence of myocardial damage. The boy was urgently taken to the cardiac catheterization laboratory for percutaneous coronary intervention, where complete occlusion of the LAD was found and successfully stented. Eventually, a peripheral blood smear showed pancytopenia with 38 % hypergranular blast-like cells consistent with acute myeloid leukemia (AML), and chemotherapy with all-transretinoic acid was implemented. This first pediatric case report of an AML-associated AMI emphasizes the benefit resulting from expedient reperfusion of the ischemic myocardium by quick reestablishment of coronary perfusion. It also emphasizes the limitations of existing noninvasive technologies in detecting myocardial viability.