Abstract: 3-Butyl phthalide was found to have anticonvulsant activity in animal experiments. In the present study, a model of chronic epilepsy was induced by im coriaria lactone 0.9～1.5 mg/kg in rats for 3 months. Ag-1 700 mg/kg ig was shown to prolong the latent period of the epileptic seizures, reduce the severity of the seizures and the number of animals with seizures. Of particalar importance is the fact that, no evidence of lesions in the cerebral neurons, glial cells and cerebellar Purkinje's cells of the Ag-1 treated animals was observed in histological studies. This result is especially encouraging as Ag-1 may have a protective effect on rat brain cells.