Abstract: Objective To evaluate the feasibility of using small interfering RNA (siRNA) for selective inhibiting latent membrane protein-1 (LMP1) expression in Epstein-Barr virus (EBV)-positive nasopharyngeal carcinoma (NPC) cell line C611, and observe the effects of LMP1 gene silencing on the NPC cell growth. Methods Four synthesized double-strand siRNA were respectively transfected into NPC cells, using Oligofectamine^TM reagent. The subsequent changes in LMP1 mRNA level were determined by semi-quantitative reverse transcriptase (RT)-PCR. Flow cytometry and MTT assay were employed to examine the alterations in cell cycle and cell proliferation. Results The most effective sequence was identified among the 4 candidate siRNAs, and its single dose caused nearly 90% loss of LMP1 mRNA in C611 cells, with sustained specific inhibition for 96 h following a re-transfection. LMP1 siRNA treatment resulted in cell cycle arrest at G₀-G₁ phase, accompanied by a reduction of cell proliferation by 33%, whereas EBV-negative NPC cells appeared unaffected. Conclusions EBV-encoded LMP-1 is vulnerable to RNA interference and selective inhibition of LMP1 suppresses the proliferation of EBV-positive NPC cells, a finding that sheds light on the possible use of RNA interference in further investigations of LMP1 and for therapeutic purposes of EBV-related NPC.