Background:Studies on electrophysiological characteristics of patients with epilepsy and concomitant psychosis are limited. We aimed to investigate the clinical and video-electroencephalography (EEG) findings of patients with epilepsy-related psychosis (EP).Materials and Methods:Fifteen patients diagnosed with EP, assessed at the video-EEG monitoring unit and were under follow-up at both epilepsy and psychiatry clinics, were included. A total of 67 nonpsychotic epilepsy patients, investigated at the video-EEG monitoring unit were randomly selected as the control group and compared statistically with the EP group.Results:In medical history, patients with EP had experienced significantly higher level of status epilepticus (P=0.002) and perinatal cerebral injury (P=0.04), whereas drug-resistant epilepsy was detected at a lower level (P=0.015). With respect to seizure onset zone, the EP group had significantly more seizures of unknown foci, whereas the control group had mostly temporal lobe origin (P=0.0004). EEG findings showed that slow background activity was significantly common among patients with EP (P=0.009). Although only 5 of 15 patients with EP had been operated, 43 of 67 patients had undergone epilepsy surgery (P=0.04) in the control group. However, there was no significant difference between the 2 groups with respect to postoperative seizure control as per Engel classification.Conclusions:Although our sample size could be considered small, slowed EEG background activity, and the marked frequency of initial precipitant factors such as status epilepticus, perinatal cerebral injury, and detected neuronal autoantibodies suggested that EP is associated with more extensive involvement. EP is not a contraindication for epilepsy surgery, when appropriately investigated preoperatively.