The development of amygdaloid kindling was assessed following preconditioning with Acorus calamus (AC) of the chronically prepared rats. The result demonstrated that chronic treatment with AC (200 mg/kg, p.o.) significantly decreased epileptogenesis. The number of kindling trials required to reach the generalized convulsions was significantly decreased by pretreatment with AC in comparison with kindled animals. Preconditioning the kindled animals with AC for 14 days markedly reduced the development of amygdaloid seizure, intensity of fit and duration of after-discharge together with an increase in the norepinephrine, serotonin and decrease in dopamine content in discrete brain regions. Analysis of behavioural studies indicated a significant decrease in seizure stages and duration of amygdaloid afterdischarges. These results reveal that AC possibly modifies the brain functions by modulating the brain monoamines and behavioural as well as electrographic discharges. Results from this study suggest that AC functions by focal sensitization of monoamines mediated inhibitory mechanism and reflecting the inhibitory influence of AC in regulating the development and attenuation of epileptic states. © VSP 2005.