Albizia myriophylla Benth. is used traditionally in the making of Hamei, a fermented product which is added to produce better quality alcohol in Manipur, India. The plant is also known to possess medicinal value in other parts of the world. This study aims to assess the effect of A.myriophylla bark aqueous extract on the central nervous system in mice. The extract was administered at a dose of 30 mg/kg and 60 mg/kg BW for 7 days and were subjected to various behavioral study such as locomotor activity, elevated plus maze test and forced swimming test. The activities of the catalase and lactate dehydrogenase were estimated in the cerebral cortex and midbrain of the mice. The ultrastructural changes induced by the plant extract was also studied using transmission electron microscopy. The results showed a decrease in the locomotor activity, an increase in the immobility time and did not cause anxiolytic effect. The plant extract significantly decreased the activity of catalase and increased the activity of lactate dehydrogenase in cerebral cortex and midbrain. The ultrastructural examination of cerebral cortex also showed deleterious effect in the treated mice. Based on the present findings we can conclude that administration of aqueous extract of A.myriophylla bark have potential neurotoxic effect on mice.