Genetic testing is increasingly becoming possible for diagnosis, susceptibility testing, and prognostication in cardiovascular medicine. The practicing cardiologist, therefore, needs to be familiar with the clinical utilities and limitations of genetic testing. This review explores the major approaches to genetic testing and issues in test interpretation. Specific applications to cardiovascular diseases, including coronary artery disease, cardiomyopathies, cardiac arrhythmias, and pulmonary arterial hypertension are discussed. © 2007 American College of Cardiology Foundation.