Objective To determine the effects of nerve regeneration factor (NRF) on neurite growth in cultured hippocampal neurons of rats. Methods After different periods (6h, 12h, 24h) of incubation by different concentrations (0.25mg/L, 0.5mg/L, 1.0mg/L) of NRF, the hippocampal neurons were observed and photographed by phase contrast microscopy, and the neurite length was analyzed using the Scion software. Realtime fluorescence quantitative RT-PCR was performed to examine the mRNA levels of growth associated protein 43 (GAP-43) after different incubation periods with different concentrations of NRF. Fluorescent immunocytochemistry and Western blotting were performed to further examine the protein levels of GAP-43 in cultured hippocampal neurons after 24h incubation with different concentrations of NRF. Results NRF promoted the neurite growth of cultured hippocampal neurons with the most obvious mophological changes appearing upon treatment with NRF at 1mg/L for 24 hours. Realtime fluorescence quantitative RT-PCR showed that the mRNA level of GAP-43 in cultured hippocampal neurons was upregulated by NRF in a dose and timedependent manner, with the best concentration of 1mg/L. Meanwhile, fluorescent immunocytochemistry and Western blotting showed that the protein level of GAP-43 was upregulated by NRF with the best concentration of 1mg/L. Conclusion NRF could promote the neurite growth and modulate the expression of GAP-43 in cultured hippocampal