Advances in medical diagnosis reveal that coronary artery aneurysms (CAAs) may develop in several clinical scenarios and manifest variable symptoms, imaging appearances, and outcomes. Aneurysms are pathologically classified into three groups: atherosclerotic, inflammatory, and noninflammatory. The last category is associated with congenital, inherited, and connective tissue disorders. Overlap exists among the groups, because secondary atherosclerotic change may be present in an aneurysm of any cause. Atherosclerosis is the most common cause of CAAs in adults, and inflammation is considered the underlying mechanism. In children, Kawasaki disease is the most likely cause of CAAs. In both conditions, the aneurysms are usually multiple and affect more than one coronary artery. Mycotic (infectious), iatrogenic, and cocaine-induced CAAs are also well documented. Most CAAs are discovered incidentally, but potential cardiovascular complications include thrombosis, occlusion, fistula formation, rupture, myocardial infarction, and cardiac tamponade. Imaging modalities to evaluate a suspected CAA include transthoracic echocardiography, angiographic cardiac catheterization, electrocardiographically gated computed tomographic angiography, cardiac magnetic resonance (MR) imaging, and MR angiography. Management is usually individualized, and options include surveillance, anticoagulant therapy, percutaneous stent or coil placement, surgical resection, and coronary artery bypass grafting.