Between 1958 and 1968, 14 patients from the epilepsy clinic at the University of Oregon Hospitals and Clinics with a diagnosis of temporal lobe epilepsy (TLE) had a temporal lobectomy for medically intractable seizures. Nine of the 14 patients operated on remained seizure-free over the 20-30-year period of follow-up. Between 6 months and one year following temporal lobectomy, two women, previously healthy from a psychiatric standpoint, developed psychoses, and the previous psychiatric problems of four other patients worsened. Two patients, one with incapacitating paranoid personality disorder and the other with explosive rage attacks preoperatively, had marked improvement in their psychiatric status following temporal lobectomy. The remaining six patients, all psychiatrically healthy prior to surgery, have had no change in psychiatric status following surgery. Development of psychosis or deterioration in psychiatric status after surgery was more common in patients with later age of onset, unreality or déjà vu rather than epigastric aura, pre-operative evidence of bilateral brain damage, and persistence of EEG or clinical seizure activity. Development of a chronic psychosis in psychiatrically healthy individuals many months after temporal lobectomy, even when seizures are arrested or ameliorated, suggests that anomalous synaptic regeneration may follow the surgery in these cases. Careful analysis of histories and outcomes may contribute to better understanding of the pathophysiology and anatomical substrates of psychoses.