Personality and behavioral changes in epilepsy are well documented. However, neither the quantitative characteristics nor the etiology of these changes is clear yet. Cloninger has developed a psychobiological personality model that provides a way to evaluate personality in a dimensional way. This study examined the relationship between epilepsy and Cloninger's dimensional psychobiological personality model. A total of 73 epilepsy outpatients and 79 healthy controls were examined using the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Axis I Disorders, the Turkish version of the Temperament and Character Inventory, and an epilepsy questionnaire. Epilepsy patients had higher harm avoidance ( HA) and lower persistence, self-directedness (SD), and cooperativeness scores than healthy controls did. In epileptic subjects, there was no correlation between age and duration of epilepsy. Subjects with partial seizures had higher HA scores and lower SD scores than generalized ones. Comorbid depression was represented with lower SD scores. In multiple linear regression models, only major depressive disorder predicted lower scores of SD. This study confirms specific personality changes among epileptics according to Cloninger's dimensional personality model and indicates a relationship between the characteristics of epilepsy and psychiatric comorbidity.