Objective　To study the plasticity of hippocampal formation in epilepsy.Methods　The optical density (OD)of synaptophysin positive immunoreactive product was examined by image pattern analysis instrument in hippocampus of pentylenetetrazol induced kindling epileptic rats. The examined areas included CA1,CA3 and the dentate gyrus.Results　The OD of synaptophysin positive immunoreactive product in hippocampal formation of kindling group was higher than the controls,especially in the mossy fiber layer of the area CA3 and the inner molecular layer in the dentate gyrus. Conclusion　The change of synaptophysin resulted from kindling, it also could result in the molecular elements of kindling maintenance.