In medical terminology, Battle's sign, also mastoid ecchymosis, is an indication of fracture of posterior cranial fossa of the skull, and may suggest underlying brain trauma. 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. The sign is named after William Henry Battle.
Another common bruising sign of a skull injury is raccoon eyes, the purplish discoloration around the eyes following fracture of the frontal portion of the skull base.
Battle's sign may be confused with a spreading hematoma from a fracture of the mandibular condyle, which is a less serious injury.