ZFX (zinc finger protein, X-linked) gene locus on the human X chromosome is structurally similar to the zinc finger protein, Y-linked gene, which may constitute the primary sex-determining signal. However, the pathological roles of the dysfunction of ZFX gene in human disease such as cancer have not been addressed. Here, we analyzed the expression of ZFX in human laryngeal squamous cell carcinoma (LSCC) tissue specimens and found a significant up-regulation compared to corresponding non-tumorous LSCC tissue. Recombinant lentivirus expressing ZFX short hairpin RNA (shZFX) was constructed and infected Hep-2 human LSCC cells. We found that knockdown of ZFX gene resulted in suppression of proliferation and colony-forming ability of Hep-2 cells, and led to S phase cell cycle arrest. In addition, down-regulation of ZFX induced a significant enhancement of cell apoptosis and expression changes of apoptosis-related genes. These results suggest that high expression of ZFX is associated with LSCC progression and knockdown of ZFX may block tumor cell growth mainly by promoting cell apoptosis.