Background: Coronary artery aneurysms are reported in 1.5 to 4.9 percent of the population receiving coronary angiography. Whether there is coronary stenosis or atrial fibrillation, it might result in an acute coronary syndrome. Case presentation: The patient was in his usual health when he began to experience pain while watching television an hour before his visit to the emergency department . The patient, a smoker with a history of hypertension, presented at our hospital with significant retrosternal chest pain. A CT angiography of the coronary arteries revealed a large RCA aneurysm thrombus-laden aneurysm. He was given 324 mg aspirin, 400 mcg Nitro-glycerin, 80 mg Atorvastatin, and a Heparin infusion immediately. An emergency RCA bypass grafting procedure was performed after a cardiothoracic surgical team assessed the patient. Conclusion: Coronary artery aneurysm is an infrequent disorder that can appear in a variety of ways. Before any further therapy, it should be thoroughly evaluated.