Object. Patients with head injuries traditionally were categorized on the basis of whether their lesions appeared to be diffuse, focal, or mass lesions on admission computerized tomography (CT) scanning. In the classification of Marshall, et al., the presence of a hematoma (evacuated or not evacuated) is more significant than any diffuse injury (DI). The CT scan appearance after evacuation of a mass lesion has not been analyzed previously in relation to outcome. The authors have investigated the importance of: 1) neurological assessment at hospital admission; 2) the status of the basal cisterns and associated intracranial lesions on the admission CT scan; and 3) the degree of DI on the early CT scan obtained after craniotomy to identify patients at risk for development of raised intracranial pressure (ICP) and lowered cerebral perfusion pressure (CPP) and to discover the influence of the postoperative CT appearance of the lesion on patient outcome.Methods. The authors prospectively studied 82 patients with isolated, severe closed head injury (Glasgow Coma Scale [GCS] score ≤ 8), all of whom had intracranial hematoma. Both ICP and CPP were continuously monitored, and a CT scan was obtained within 2 to 12 hours after craniotomy. The CT images were categorized according to the classification of Marshall, et al.The mortality rate during the hospital stay was 37%, and 50% of the patients achieved a favorable outcome. Compression of the basal cistern on the admission (preoperative) CT scan was associated with raised ICP and a CPP of less than 70 mm Hg but not with any other features or with poor patient outcome. In 53 patients the postoperative CT scan revealed DIs III or IV and 29 patients had DIs I or II. The percentages of time during the hospital stay in which ICP was higher than 20 mm Hg and CPP was lower than 70 mm Hg as well as unfavorable outcome were higher in the group of patients in whom DI III or IV was present (p < 0.001). Raised ICP, CPP lower than 70 mm Hg, DI III or IV, and unfavorable outcome were more frequently observed in patients who presented with a motor (m)GCS score of 3 or less, bilateral unreactive pupils, associated intracranial injuries, and hypotension (p < 0.001). When logistic regression analysis was performed, an mGCS score of 3 or less (p = 0.0013, odds ratio [OR] 10.8), bilateral unreactive pupils (p = 0.0047, OR 31.8), and DI III or IV observed on CT scanning after surgery (p = 0.015, OR 8.9) were independently associated with poor outcome.Conclusions. Features on CT scans obtained shortly after craniotomy constitute an independent predictor of outcome in patients with traumatic hematoma. Patients in whom DI III or IV appears on postoperative CT scanning, who often present with an mGCS score of 3 or less and nonreactive pupils, are at high risk for the development of raised ICP and lowered CPP.