Sodium valproate has been reported to be effective in the treatment of recurrent major affective and schizoaffective disorders. The records of 36 consecutive patients with various psychiatric diagnoses, who received valproate at our center, were retrospectively reviewed. None of these patients displayed a diagnosable neurologic disorder or paroxysmal EEG activity. Sixteen (44%) of the 36 patients experienced a moderate to marked response to valproate. The diagnoses of bipolar or schizoaffective disorder and the presence of non-paroxysmal EEG abnormalities both predicted a favorable response. The authors conclude that valproate deserves further study as a possible treatment for major affective disorder.