ntroduction: Nasopharyngeal carcinoma (NPC) is a prevalent cancer among human population in Southern China, Hong Kong and Southeast Asia. In Malaysia, NPC is the fourth most common cancer in both sexes, predominantly in the Chinese. Epstein-Barr virus (EBV) infection is known to be highly associated with NPC. Fibroblast growth factor receptor-4 (FGFR4) is part of the family of tyrosine kinase receptors that regulate cell survival, differentiation and pro-liferation. The binding of FGFR4 ligands such as fibroblasts growth factors (FGFs) has been shown to activate various oncogenic signalling pathway including MAPK, Ras and PI3K-Akt pathways. In the past, FGFR4 has been shown to promote tumorigenesis and tumour progression in various cancers such as liver, colon, breast and pancreatic and gastric cancers. However, its role in NPC establishment and pathogenesis is under-explored. This study aimed to evaluate the FGFR4 expression in NPC using various cell lines and its potential as a therapeutic target for NPC treat-ment by gene silencing. Methods: The basal FGFR4 level of NPC (EBV-positive: C666-1 and EBV-negative: HONE1 and HK1) and nasopharyngeal epithelial (NPE) normal (NP69 and NP460) cell lines was determined by western blot analysis and RT-qPCR. FGFR4 level at different time points (0, 24, 48, and 72 hours) in HONE1 and C666-1 cell lines were determined by western blot analysis. Luminescence-based assay was performed to determine the cell prolifer-ation of NPC cells in correlation with the FGFR4 expression. NPC cells were then treated with the optimised FGFR4 siRNA or FGFR inhibitor, BLU-9931 and the silencing/ inhibition of FGFR4 expression was confirmed by western blot analysis. The effect of FGFR4 inhibition on the cell proliferation and aggressiveness of NPC cells was then investigat-ed through wound healing assay and invasion marker analysis. Results: Out of the five tested cell lines, HONE1 and C666-1 highly expressed FGFR4, NP69 showed very low expression while HK1 and NP460 did not express FGFR4. In the time-point study, the FGFR4 level of HONE1 and C666-1 peaked at 24-48 hours which is the exponential phase of cells. Following that, the FGFR4 level decreased corresponding to the decreased cell growth rate due to the nutrient deprivation. siRNA experiments showed that 6.25nM of four siRNAs (5, 6, 9 and 10) could effectively target and silence the FGFR4 expression of HONE1, but not in C666-1 even up to 250nM was tested. When BLU-9931 was used, only modest inhibition was observed in both cells at 3uM. Compared to the untreated control, FGFR4-inhibited HONE1 exhibited decreased cell proliferation rate. Cell migration and invasion capabilities of HONE1 were also significantly reduced following the FGFR4 silencing, suggesting the potential of utilising FGFR4 as the therapeutic target. Conclusion: FGFR4 is highly expressed in C666-1 (EBV-positive) and HONE1 (initially EBV-positive, but lost EBV genome in subsequent in vitro passage) NPC cells, but not in EBV-negative HK1 NPC cell and normal NPE cells. FGFR4 gene silencing effectively inhibited the cell proliferation, migration and invasive potentials of NPC cell line. These findings highlight the therapeutic value of targeting FGFR4 for NPC treatment. Further investigations are war-ranted to reveal the molecular mechanism and the possible role of EBV in regulating FGFR4 pathway.