Status epilepticus (SE) can be induced with homocysteine after pretreatment with cobalt. In order to investigate the pattern of neuronal changes in the hippocampus in cobalt/homocysteine-induced SE, H-E staining and immunohistochemistry for c-Jun were performed in the brain after SE. Neuronal damage was not seen in the hippocampus in cobalt-treated control rats. Neuronal injury occurred in 14% of the cells in the hilus 24 hrs after SE. The neuronal injury was minimal in the dentate gyrus (DG), CA3, and CA1 24 hrs after SE. c-Jun immunoreactivity was detected strongly in the DG and CA3 2 hrs after SE, and then c-Jun immunoreactivity was decreased to that of control rats in the hippocampus 24 hrs after SE. These results suggest that upregulation of c-Jun expression in the hippocampus is not related to neuronal death in cobalt/homocysteine-induced SE, secondary generalized epilepsy originating from the cerebral cortex does not cause significant hippocampal cell injury.