Decisions about the optimal imaging strategy in patients after acute head trauma can be based on clinical observations. Low-risk patients do not require radiographic imaging. CT is the procedure of choice for imaging moderate- and high-risk patients after head trauma. Because of its limited ability to guide therapy, plain skull radiography should be used sparingly; it may be useful in equivocal cases of bony injury not detected by CT or in selected moderate-risk patients (especially children under the age of 2 years). MR imaging rivals CT in the detection of intracranial injuries but is more expensive and cumbersome in seriously ill subjects and does not image bony structures. MR imaging is recommended after initial CT if subtle acute nonhemorrhagic and subacute hemorrhagic lesions are suspected, especially in the evaluation of child abuse. Otherwise, MR imaging is rarely needed in the emergency department management of acute head injury patients.