Military health care professionals serve in a variety of settings, more diverse than is typically found in the civilian environment. The Military Health System (MHS) is a global, comprehensive, integrated system that includes combat medical services, peacetime health care delivery to Service members and eligible beneficiaries, public health services, medical education and training, and medical research and development. MHS personnel provide a continuum of health services from austere operational environments through remote, fixed military treatment facilities (MTFs), to major tertiary care medical centers distributed across the United States. Military health care professionals are also expected to care for detainees, enemy combatants, nonstate actors, local nationals, and coalition forces. In addition, U.S. military personnel are often deployed to assist in humanitarian missions, such as natural disasters or to provide care to local citizens in combat zones. Directly applying ethical principles from civilian medical ethics may not be appropriate in military medicine. The basic discrepancy between the two settings involves their goals and how these goals can be achieved. This book examines the ethical guidelines, practices, and issues for U.S. military medical professionals.