Depression is common in epileptics, but few studies of this relationship exist. We investigated the prevalence of depression in comparably disabled outpatients and its phenomenology in psychiatrically hospitalized inpatients. Fifty-five percent of 175 outpatient epileptics and 30% of 70 matched controls reported depression; 30% of epileptics vs 7% of controls reported prior suicide attempts. Epileptics were four times more likely to have been hospitalized for depression than nonepileptics. Twenty depressed epileptic inpatients were characterized by "endogenous" rather than "neurotic" features with more psychotic traits, paranoia, and underlying chronic dysthymia. Sixteen patients had complex partial seizures, and ten of 11 patients had a lateralized electroencephalographic focus lateralized to the left hemisphere. These results suggest a specific epileptic psychosyndrome due to limbic dysfunction.