Since symptoms of chronic dissociative disorders such as multiple personality disorder (MPD) may be shared by patients with seizure disorders, we investigated the possible relationship between dissociative states and epilepsy. We monitored 6 MPD patients with intensive video-EEG recordings to determine whether epileptic phenomena have any correlation to the dissociative symptoms experienced by these patients. Previously, physicians had diagnosed epilepsy in all 6 patients; however, none proved to have epilepsy. In addition, we studied dissociative symptoms in 71 epileptic patients with the aid of a standardized questionnaire, the Dissociative Experiences Scale, and compared them with age-matched controls. While the group median score of cases with complex partial seizures was higher than that of normal controls, it was significantly lower than that of the psychiatric patients with MPD. Partial seizure patients with dominant hemisphere foci had higher depersonalization subscale scores than those with nondominant foci. Our data suggest that epilepsy is not a primary pathophysiologic mechanism for developing dissociative symptoms.