Background. Acute myocardial infarction among the young population is rare and presents diagnostic and approach difficulties that lead to treatment delay in emergency cases and worse outcome for patients. This case focuses on a young man who developed an inferior myocardial infarction as a result of embolization of the left coronary artery system associated with the right coronary anomaly. Case report. A 25 year old man presented in the emergency room with a 4 hours history of severe retrosternal crushing pain, radiating down his left arm and associated with sweating, nausea, and breathlessness. He had never previously experienced chest pain at rest or on exertion. He was a smoker. The last 2 weeks have been really stressful so the patient smoked more than usual. He didn’t have a family history of ischaemic heart disease or sudden cardiac death. At first examination he was pale and sweaty with a tachycardia of 110 beats/min. His blood pressure was 140/100 mm Hg. Transthoracic echocardiography revealed hypokinesia of the inferior wall. A coronary angiogram showed the absence of right coronary ostium (ostial trombosis?) and filling of the right coronary artery through collateral vessels from the left coronary system; LAD and OM I distal thrombosis. No right coronary ostium was observed in the aortogram. None of the coronary arteries showed any sign of atherosclerosis. We performed thrombolysis (Actilyse) with clinical and ECG improvement. After 72 hours angiography - LAD and OM I successful total trombolysis, couldn't find RCA origin - suspicion of anomalous origin of the right coronary artery. The patient was discharged on the 5th day of hospitalization in good condition. Recommended: hereditary screening thrombophilia panel and Coronary CT Angiography (CTA). CTA showed - Anomalous Right Coronary Artery From the Left Coronary Sinus With an Interarterial Course, as well as right coronary artery ostial and proximal hypoplasia, and a fistule LAD pulmonary artery RCA.Conclusions.1. Congenital ostial coronary artery atresia/hypoplasia should be a part of the differential diagnosis particularly in young patients presenting with a totally occluded coronary artery and no cardiovascular risk factors. 2. Thrombolysis can be a good choice for treatment of STEMI if primary PCI has failed. 3. Patients with suspicion of anomalous coronary arteries should perform CT angiography (CTA) to confirm originated sites, anatomic route and whether complicated with other congenital malformation.