A cervical collar, also known as a neck brace, is a medical device used to support and immobilize a person's neck. It is also applied by emergency personnel to those who have had traumatic head or neck injuries, and can be used to treat chronic medical conditions.

Whenever people have a traumatic head or neck injury, they may have a cervical fracture. This makes them at high risk for spinal cord injury, which could be exacerbated by movement of the person and could lead to paralysis or death. A common scenario for this injury would be a person suspected of having whiplash because of a car accident. In order to prevent further injury, such people may have a collar placed by medical professionals until X-rays can be taken to determine if a cervical spine fracture exists. Medical professionals will often use the NEXUS criteria and/or the Canadian C-spine rules to clear a cervical collar and determine the need for imaging. The cervical collar only stabilizes the top seven vertebrae, C1 through C7. (Other immobilizing devices such as a Kendrick Extrication Device or a backboard can be used to stabilize the remainder of the spinal column.)

The routine use of a cervical collar by a first aid provider is not recommended.

Cervical collars are also used therapeutically to help realign the spinal cord and relieve pain, although they are usually not worn for long periods of time. Another use of the cervical collar is for strains, sprains, or whiplash. If pain is persistent, the collar might be required to remain attached to help in the healing process. A person may also need a cervical collar, or may require a halo fixation device to support the neck during recovery after surgery such as cervical spinal fusion.