The p75 pan-neurotrophin receptor (p75(NTR)) plays a pivotal role in linking the immune system with the nervous system. p75(NTR) is required for the development of several characteristic features of allergic asthma. Also p75(NTR) upregulated by reactive Schwann cells after peripheral nerve injury. Moreover p75(NTR) and RhoA play a critical role in the regulation of apoptosis. To determine whether the designed siRNA for p75(NTR) can downregulates both p75(NTR) and Rho-A at RNA level in rats and, if so, at what magnitude, Schwann cell apoptosis occurs. Isolation and purification of neonate Schwann cells were prepared from rat sciatic nerve. Specific siRNA duplex was designed for p75(NTR) . To investigate the role of siRNA-mediated knockdown of p75(NTR) , the gene expression in p75(NTR) was examined with reverse transcription-polymerase chain reaction (RT-PCR) and Real-Time RT-PCR. Schwann cell apoptosis was performed by Annexin and TUNEL assays after 24 hours. Following p75(NTR) Transfection siRNA, p75(NTR) gene, compared with control, was downregulated by 73%. Without using siRNA for Rho-A, Rho-A gene was downregulated by 89% at the same time. Based on Annexin assay, apoptosis of Schwann cells occurred in siRNA+NGF and control+NGF by 16.76%±2.27 and 92.39%±1.82, respectively. TUNEL data showed that apoptosis of Schwann cells occurred in siRNA and control by 12.91%±6.39 and 78.55%±11.85, respectively. Thus, p75-siRNA downregulated both p75(NTR) and Rho-A at RNA level in rats and showed a role on decreased cell apoptosis compared to the controls.