Hospital Emergency Codes are used in hospitals worldwide to alert staff to various emergency situations. The use of codes is intended to convey essential information quickly and with a minimum of misunderstanding to staff, while preventing stress or panic among visitors to the hospital. These codes may be posted on placards throughout the hospital, or printed on employee/staff identification badges for ready reference.

Hospital emergency codes may denote different events at different hospitals, even nearby ones. Since many physicians have privileges at more than one facility, this may lead to confusion in emergencies, so uniform systems have been proposed.

Note: Different codes are used in different hospitals.

"Code Blue" is generally used to indicate a patient requiring resuscitation or otherwise in need of immediate medical attention, most often as the result of a respiratory arrest or cardiac arrest. When called overhead, the page takes the form of "Code Blue, (floor), (room)" to alert the resuscitation team where to respond. Every hospital, as a part of its disaster plans, sets a policy to determine which units provide personnel for code coverage. In theory any medical professional may respond to a code, but in practice the team makeup is limited to those with Advanced Cardiac Life Support or other equivalent resuscitation training. Frequently these teams are staffed by emergency department and intensive care unit physicians, respiratory therapists, and nurses. At least one attending physician must be in attendance on any code team; this individual is responsible for directing the resuscitation effort and is said to "run the code." This phrase was coined at Bethany Medical Center in Kansas City, Kansas. The term "code" by itself is commonly used by medical professionals as a slang term for this type of emergency, as in "calling a code" or describing a patient in arrest as "coding".