We investigated anatomic alterations and lateralization effect in the mesial temporal lobe structures (amygdala and hippocampus) in epileptic psychosis MRI volumetric measurements. Patients with epileptic psychosis and normal controls were studied. Left hippocampus values were significantly smaller for patients (P<0.001). Hippocampal ratio was significantly greater for patients (P<0.01). Group (patients x normal) was the only factor explaining the statistically significant variation of left hippocampus and hippocampal ratio (P<0.001 and P<0.05). Twenty patients had hippocampal atrophy (4 on the right side, 15 on the left side, and 1 bilateral) associated with mesial temporal sclerosis. These results confirm the existence of anatomic alterations and a left laterality effect in the mesial temporal lobe structures of patients with epileptic psychosis.