This article reviews the neuroradiological evaluation of acute head injury with an emphasis on CT and MR imaging. Subacute and chronic head injury are not discussed. CT remains the modality of choice in the emergency setting, permitting rapid, comprehensive assessment of the great majority of head injuries. MR is most useful in patients in whom there is a discrepancy between clinical symptoms and CT findings. In addition, MR is the imaging modality of choice in the subacute and chronic setting. The superior contrast resolution of MR permits optimal evaluation of nonhemorrhagic (and hemorrhagic) white matter shearing injuries, and the lack of beam-hardening artifact permits a more thorough evaluation of the brain stem, posterior fossa, and cortical surface.