Abstract-Medical directors of cardiac rehabilitation/secondary prevention (CR/SP) programs are responsible for the safe and effective delivery of high-quality CR/SP services to eligible patients. Yet, the training and resources for CR/SP medical directors are limited. As a result, there appears to be considerable variability throughout CR/SP programs in the United States in the roles, responsibilities, and engagement of CR/SP medical directors. Since the publication of the 2005 scientific statement from the American Heart Association and American Association of Cardiovascular and Pulmonary Rehabilitation regarding medical director responsibilities for outpatient CR/SP programs, significant changes have occurred. This statement updates the responsibilities of CR/SP medical directors, in view of changes in federal legislation and regulations and changes in health care delivery and clinical practice that impact the roles and responsibilities of CR/SP medical directors. (Circulation. 2012;126:2535-2543.)Key Words: AHA Scientific Statements Ⅲ cardiac rehabilitation Ⅲ exercise training Ⅲ medical director O utpatient cardiac rehabilitation/secondary prevention (CR/SP) programs are recognized as a key component of the management of patients with a variety of cardiovascular conditions, including stable angina, recent myocardial infarction or acute coronary syndrome, or heart failure, or following coronary revascularization procedures, valve surgery, or cardiac transplantation. In addition to improving adherence to medication regimens and lifestyle recommendations, enhancing quality of life and psychosocial wellbeing, and increasing functional capacity, recent research has shown that participation in CR/SP programs reduces 5-year mortality by 25% to 46% and recurrent nonfatal myocardial infarction by 31%. [1][2][3] Similar to many other therapeutic interventions, there is evidence that those who participate in more CR/SP sessions obtain greater benefits. 1,3 As a result, referral to CR/SP programs is currently included in numerous clinical guidelines, with a high level of evidence and strength of recommendation. 4 -11 In addition, referral to CR/SP programs is incorporated into performance measure sets for myocardial infarction and chronic oronary artery disease. 12,13 From Helen Hayes Hospital, West Haverstraw, New York, and Columbia University, New York, New York (M. Legislation passed by the US Congress in 2008 stipulated that a medical director is required for the operation of CR/SP programs, and that CR/SP is defined as "a physician supervised program that furnishes physician prescribed exercise, cardiac risk factor modification, psychosocial assessment, and outcomes assessment" (italics added). 14 As a result of this legislation and changes in the science and practice of CR/SP, the American Association of Cardiovascular and Pulmonary Rehabilitation (AACVPR) and the American Heart Association (AHA) deemed it important and necessary to update the 2005 AACVPR/AHA statement on the roles and responsibilities of CR/SP m...