A retrospective comparative study of MRI and CT in 24 patients with diffuse axonal injury (DIA) was undertaken. Three-quaters of the lesions were non-hemorrhagic, and the sites of involvement were lobar white matter (96%), corpus callosum (70%), and rostral brainstem (42%), in descending order. MRI was singnificantly more sensitive than CT in detecting DAI lesions. The average number of DAI lesions was higher with increasing clinical stage of the injury. MRI is more valuable than CT for staging the full magnitude of the injury and in predicting the neurologic prognosis of DAI lesions.