The sensitivity and specificity of CT and high-field MR (1.5 T) were compared in an evaluation of 30 patients with head injuries (eight acute, 15 subacute, and seven chronic). By using T1- and T2-weighted images, it was possible to detect various stages of hemorrhages and their separation from edema. In the acute category, both CT and MR showed acute hemorrhagic lesions, but only MR demonstrated coexisting chronic hematomas or small hypothalamic or brainstem infarctions. MR was far superior to CT in the detection and characterization of subacute injuries, including shearing injuries, hemorrhagic and nonhemorrhagic contusions, and subdural hematomas. In chronic injury, atrophy was demonstrated by both techniques, but only MR showed parenchymal abnormalities and old hemorrhages. Its ease in monitoring patients and its greater speed make CT the procedure of choice for the evaluation of acute cases. CT also provides information that is useful in deciding between surgery and medical management. However, the more precise anatomic depiction of MR and its sensitivity to parenchymal abnormalities make MR the key to correct prognosis in patients with subacute or chronic injury.