Abstract: Objective: To investigate the effect on the proliferation and the apoptosis of the human tongue squamous carcinoma cell line SCC9 through exogenous inhibition of Neuropilin-1(NRP-1). Methods: Western blot and real-time RT-PCR were employed to examine the effect on the expression of NRP-1 in cell line SCC9 exogenous inhibition of NRP-1. Besides, cell counting and flow cytometry(FC) methods were used to examine the influence of the proliferation and the apoptosis of the SCC9 cells exogenous inhibition of NRP-1. Results: After the inhibition, mRNA level of NRP-1 decreased, whereas the expression of protein level of NRP-1 did not decrease obviously. Exogenous inhibition of NRP-1 enhances the apoptosis of SCC9 cells while rarely affects the proliferation of SCC9 cells. Conclusions: Exogenous inhibition of NRP-1 enhances the apoptosis of the SCC9 cells.