Medical evacuation, often termed Medevac or Medivac, is the timely and efficient movement and en route care provided by medical personnel to wounded being evacuated from a battlefield, to injured patients being evacuated from the scene of an accident to receiving medical facilities, or to patients at a rural hospital requiring urgent care at a better-equipped facility using medically equipped ground vehicles (ambulances) or aircraft (air ambulances).

Examples include civilian EMS vehicles, civilian aeromedical helicopter services, and Army air ambulances. This term also covers the transfer of patients from the battlefield to a treatment facility or from one treatment facility to another by medical personnel, such as from a local hospital to a trauma center.

The term medevac is commonly applied to a motor vehicle, fixed-wing aircraft, or helicopter used as an ambulance (sometimes called an "air ambulance") to provide medical care in route. This permits the rapid transport of seriously injured persons, particularly trauma patients, from the scene of the accident to the hospital. News accounts of such transportation often use the terms "airlifted" or "LifeFlighted", although medevac is a common term used by civilians as well. Most patients transported by medevac are taken to a specialized hospital known as a trauma center. Medevac can refer to either ground or air assets being utilized, the use of this term can cause confusion.