Objective To explore the relation between spatial learning and memory and expression of SDF-1 chemokin in rat hippocampal formation. Methods Immunohistochemistry, Westernblotting and RT-PCR were used to study changes of SDF-1 protein in hippocampual formation during spatial learning and memory in rats. Results 1. The immunohistochemistry result showed that the SDF-1 immunoreactive positive neurons were mainly distributed in each subregion and each layer of hippocampus, and were mainly round in shape the while positive pyramidal and fusiform neurons were rare. The number of the positive neurons was more in trained group than that in control groups(P<0.01). 2. The Western blotting result showed that expression of SDF-1 protein was significantly higher in trained group than that in control groups(P<0.01). In trained group, expression of SDF-1 was gradually increased with training. 3. The RT-PCR result showed that level of SDF-1 mRNA transcription was significantly higher in trained group than that in control groups(P<0.01), and the level of SDF-1 mRNA in the trained group was gradually increased with training duration. There was no group differences between control group and swimming group as shown by immunochemistry, Western blotting and RT-PCR shown. Conclusion The spatial learning and memory induced expression of SDF-1 in rat hippocampus and it may have relation with formation of new microcircle pathway in hippocampus during the period of spatial learning and memory.