In the present study, by means of immunohistochemical method, the contents of synaptotagmin IV in the CA1, CA3 and dentate gyrus subfields of dorsal hippocampus were measured in the middle-aged CD-1 mice, whose mothers were intraperitoneally injected with lipopolysaccharide or normal saline during late pregnancy. The results indicated that the synaptotagmin IV was expressed in each stratun of all subfields in the dorsal hippocampus. Compared to the saline-treated group, the lipopolysaccharide-treated group had an obvious increase in the expression level of synaptotagmin IV (Ps < 0.05) in each stratun of CA1 and CA3 subfields, and the stratum molecula of dentate gyrus. Our result suggested that maternal exposure to lipopolysaccharide in late gestation could increase the synaptotagmin IV level of dorsal hippocampus in middle-aged offspring mice.