An emergency physician (often called an "ER doctor" in the United States) is a physician who works at an emergency department to care for ill patients. The emergency physician is a specialist in advanced cardiac life support (advanced life support in Europe), resuscitation, trauma care such as fractures and soft tissue injuries, and management of other life-threatening situations.

In some European countries (e.g. Germany, Belgium, Poland, Austria, Denmark and Sweden), emergency physicians/anaesthetists are also part of the emergency medical service and are dispatched together with emergency medical technicians and paramedics in cases of potentially life-threatening situations for patients (heart attacks, serious accidents, resuscitations or unconsciousness, strokes, drug overdoses, etc.). In the United States, emergency physicians are mostly hospital-based, but also work on air ambulances and mobile intensive-care units.

When a patient is brought into the emergency department, they are usually sent to triage first. The patient may be triaged by an emergency physician, a paramedic, or a nurse; in the United States, triage is usually performed by a registered nurse. If the patient is admitted to the hospital, another physician such as a cardiologist or neurologist takes over from the emergency physician.