Abstract. The present study aimed to characterize the expression of Krüppel-like factor 8 (KLF8) in nasopahryngeal carcinoma (NPC) cell lines and determine its effect on tumor development and invasion following KLF8 gene knockdown by small hairpin RNA (shRNA). KLF8 expression in four NPC cell lines was examined by quantitative polymerase chain reaction (qPCR) and western blotting. KLF8 was knocked down in the SUNE1-5-8F/Sh-KLF8 cell line using shRNA, and the resulting stable cell line SUNE1-5-8F-sh-KLF8 was transplanted into nude mice in order to observe tumor formation and invasion. The results obtained from qPCR and western blotting revealed that, of the four NPC cell lines, KLF8 expression was lowest in the CNE-1 cells and highest in the SUNE1-5-8F cells. The tumor xenograft mouse models revealed that SUNE1-5-8F/Sh-KLF8 cells had a reduced ability for tumor formation and invasion compared with the control group. These results demonstrated for the first time that KLF8 modulates the formation and invasive ability of nasopharyngeal carcinoma.