The first-time appearance of a murmur in an adolescent can create a substantial amount of anxiety in the parents and the teenager. The appropriate evaluation and diagnosis is very important in decision-making regarding sports participation in this population. Accurate identification of the innocent murmurs can obviate the need for echocardiography. Identification of a pathologic murmur may reduce morbidity and, possibly, mortality in critical lesions such as hypertrophic cardiomyopathy. This article discusses the physiology and characteristics of different murmurs, and outlines an approach to cardiac murmurs in adolescents.