Since the introduction of CT in February, 1977, 64 cases with 67 traumatic extradural hematomas were experi enced. These cases were analysed, especially with regard to CT findings of the hematomas, small extradural he matomas, and combined intracerebral hematomas, and the correlation between CT gradings and clinical outcomes. From these analyses, the following results were obtained. In 64 out of 66 hematomas, except for a case of sagittal sinus hematoma, shapes were biconvex on CT scans. The

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... er two were planconvex and crescent. One sagittal sinus hematoma could not be diagnosed by CT alone because the highest parietal slice was not taken. In 60 acute hematomas, densities of 59 were high. The other one was hypo or iso-dense. In six subacute hematomas, two were hypo and iso-dense respectively. These two cases showed a marked dural enhancement for contrast material. Initial admission CT scans disclosed 35 large hematomas (> 20 mm in thickness) and 29 small ones ( ?? 20 mm). The other three were not clear in the initial CT scans. Among 12 small hematomas for which initial CT scans were performed within 6 hours after injury and sequential CT scans were carried out, six were shown to become larger. Three of these were operated on thereafter. Eleven cases with small hematomas on the initial CT scans were operated on. Their bleeding sources were the middle meningeal arteries in three cases, dural vein in one, fracture sites in four, and unclear in three. In 16 combined intradural lesions, ten were traumatic intracerebral hematomas. Four of these intracerebral hematomas were found simultaneously with extradural ones in CT scans. Six were obviously found later than the latter. Two cases with multiple extradural hematomas were reported. After evacuation of one extradural hematoma, additional extradural and intracerebral hematomas developed at other sites in these cases.