Coronary artery anomalies (CAAs) are a diverse group of congenital disorders whose manifestations and pathophysiological mechanisms are highly variable. The subject of CAAs is undergoing profound evolutionary changes related to the definition, morphogenesis, clinical presentation, diagnostic workup, prognosis, and treatment of these anomalies. To understand the clinical impact of CAAs, the fundamental challenge is the firm establishment, for a particular type of CAA, of a mechanism capable of interference with the coronary artery's function, which is to provide adequate blood flow to the dependent myocardium. The present review focuses on anomalous origination of a coronary artery from the opposite sinus--the subgroup of CAAs that has the most potential for clinical repercussions, specifically sudden death in the young. For this subgroup, solid diagnostic screening protocols should be established, especially for athletes and other young individuals subjected to extreme exertion. Intravascular ultrasonography is the preferred means to evaluate the mechanisms responsible for ischemia in anomalous origination of a coronary artery from the opposite sinus and other potentially significant CAAs. Patients symptomatic of anomalous origination of a coronary artery from the opposite sinus may undergo medical treatment/observation, coronary angioplasty with stent deployment, or surgical repair. To be competent to advise CAA carriers, especially in the context of sporting or military activities, cardiologists should undergo specific training in these disorders. Only multicenter collaboration on protocols dedicated to CAAs can give rise to the large-scale studies needed to define the prognosis and optimal treatment of these disorders.