Battle's sign, also known as mastoid ecchymosis, is an indication of fracture of middle cranial fossa of the skull.

Battle's sign consists of bruising over the mastoid process as a result of extravasation of blood along the path of the posterior auricular artery.

[1] The sign is named after William Henry Battle.

[2] Battle's sign takes at least one day to appear after the initial traumatic basilar skull fracture, similar to raccoon eyes.

Battle's sign may be confused with a spreading hematoma from a fracture of the mandibular condyle,[4] which is a less serious injury.