Objective: In this study,we used fluorogold(FG) to observe the synaptic connections among pyramidal cells in the CA1 area of the hippocampus in pilocarpine-induced epileptic rats at the chronic phase.Methods: Twenty SD rats were randomly divided into epilepsy(n=10) and control(n=10) groups.The models of epilepsy were established by intraperitoneal injections of pilocarpine and lithium.The controls were injected with normal saline.About 60 days after status epilepticus(SE),retrograde tracer FG was injected into the CA1 area of the hippocampus in vivo by using the stereotaxic apparatus.After surgery,animals were allowed to survive for 5-7 days before perfusion-fixation.Confocal microscopy was used to observe the distribution of FG.Results: Additional FG-labeled pyramidal cells were seen remote from the zone of dye spread in the CA1 area in five rats of the epilepsy group,and also additional FG-labeled pyramidal cells were seen in the subiculum in two experimental rats; additional FG-labeled pyramidal cells were not seen in the control group.Conclusions:Aberrant synaptic connections among pyramidal cells in CA1 area and aberrant connections of pyramidal cells between CA1 area and subiculum in the hippocampus might be an anatomy basis forming the aberrant excitatory circuit in rats with temporal lobe epilepsy.