Background: Acute myocardial infarction (AMI) concomitant with aortic dissection (AD) is rare but a devastating situation if misdiagnosed as simply AMI, followed by anticoagulant or thrombolytic therapy. In such cases, Standford type B AD was extremely infrequent. Objectives: To present a case with apparent concordance with the patient’s history, symptoms, cardiac enzymes that lead to diagnostic error. Case report: An 85-year-old man with chronic hypertension and coronary atherosclerotic heart disease presented in our emergency department with squeezing retrosternal chest pain and dyspnea. Elevated cardiac enzymes and electrocardiography result suggested acute non-ST-segment elevation myocardial infarction. Emergency coronary angiography demonstrated a 50-90% diffuse stenosis of the proximal and mid right coronary artery also confirmed the diagnosis. Stents were deployed thereafter. However, the patient was found to be concomitant with Standford type B AD by computed tomography angiography due to unrelieved chest pain and new onset of abdominal pain after the operation. The patient refused to have endovascular operation and died of hemorrhagic shock one week later. Conclusions: AD may cause AMI due to some indirect mechanisms, and it is of utmost importance to search for the existence of AD before reperfusion therapy in AMI patients. Aortic dissection detection risk score, transthoracic echocardiography and D-dimer help early identification of AD.