Computed tomography (CT) has revolutionized the diagnosis and management of head-injured patients, and its increasing availability has led to its liberal use. CT scanning provides excellent anatomic detail of the brain as fixed static images, but the dynamic nature of human physiology means that many injury patterns will evolve in time. We describe an 8-year-old child who had fallen 8 feet from a tree. He had a brief loss of consciousness but a normal neurologic evaluation on arrival to the emergency department (ED). He underwent expedited cranial CT scanning, which revealed no acute brain injury. Two and one half hours later, the patient had a mild depression in consciousness, prompting a second CT scan in the ED, which revealed an acute epidural hematoma. He had acute surgical evacuation of the hematoma and made a full neurologic recovery. This case illustrates that a single early CT examination may at times provide a false sense of security and underscores the importance of serial neurologic examinations.