Serial magnetic resonance imaging (MRI) and computed tomographic (CT) studies were performed in mild to moderate head injury to evaluate whether early and late imaging have additional value in predicting outcome in this category of patients. During 1-year follow-up of a series of 67 patients, a CT scan on admission was performed together with MRI studies within 1 to 3 months and 6 to 12 months after injury. With CT, intracranial lesions were seen in 62% of patients compared with 44% with early and 19% with late MRI, located predominantly in the frontal and temporal regions. More than half of the lesions revealed with CT resulted in focal atrophy on MRI. Outcome was found to be worse in patients with edema and lesions on CT. Likewise, abnormalities detected with MRI were associated with poor outcome scores. In multiple regression analysis, only lesions in the frontal regions detected with early MRI were found to be predictive of outcome. With late MRI, only focal atrophy in the frontotemporal regions was found to be predictive of outcome. The findings in this study suggests that MRI studies may be valuable for predicting long-term outcome in patients with mild to moderate HI.