Four patients had Phenytoin intoxications, whereby 3 of them suffered from acute and one from subacute symptoms (in all of them reversible cerebellar symptoms and acute organic brain syndrome and in one of them an axonal polyneuropathy which lasted a bit longer). The clinic-neurologic symptoms, the Phenytoin blood levels and the current EEG changes were compared. Three patients had blood levels in a high toxic range, the fourth one had levels within the therapeutic range. The EEG changes of acute phase of intoxications showed in each case nonspecific mostly diffused slowing of the traces with theta- and delta-activity over the convexity (Tab. 1a, 2c, d). Although the EEG changes were reversible, they lasted longer than the clinical intoxication phase. These EEG changes were already manifest several days before the clinical symptoms. We feel therefore that the EEG examination is indicated especially in doubtful cases because it is easier to execute than the blood level estimation, - even though the changes are nonspecific. One case (Nr. 1), which was more closely explores, did not develop any epileptic fits, instead the fits were retrospectively seen as stemming from a psychogenic origin, which was treated with Phenytoin. The EEG of this patient showed generalised irregular SW-paroxyms (Tab. 1b) as the medication blood level was receding (120 muMol/l). This would be a manifestation of an independent Phenytoin effect in the high toxic dosage respectively in withdrawal.