Among 83 head-trauma cases examined by CT scan in a later year, 41 were included in a seizure group of those who clinically showed late epilepsy and who obviously showed epileptic discharge such as spike or spike and wave in EEG after trauma, and 42 were included in a nonseizure group of those who had some sequelae such as abnormal findings in EEG or neurologic defects: the CT findings of these 83 cases were collected and compared with clinical findings, EEG, and other data. The CT findings of these cases were divided into five groups: (A) a normal group; (B) a group showing partial or unilateral ventricular dilatation; (C) a group showing porencephaly in the cerebral parenchyma; (D) a group suspected of cortical atrophy; (E) a group of other cases. Group D contained 44.3% of the cases, and was the largest group; the frequency of seizure was highest in Group C. The CT classification reveals the contradiction of the conventional definition of posttraumatic epilepsy and also poses some problems concerning the disease. CT scan is mostly applied to head trauma in the acute stage, and as for trauma in the chronic stage there are a few reports on chronic subdural hematoma and post-traumatic hydrocephalus. We noticed posttraumatic epilepsy among the sequelae of trauma, and then analyzed CT findings of the epilepsy: the results are reported here.