Zinc finger protein, X-linked (ZFX) is a transcription factor encoded by its gene on the mammalian X chromosome, and functions to control survival and activity of stem cells and lymphocytes. However, little is known about the role of ZFX in tumorigenesis. The function of ZFX in cell proliferation was investigated by the lentivirus-mediated short hairpin RNA interference (shRNA) approach in non-small cell lung cancer (NSCLC) cell culture lines. The expression profiles of ZFX in 49 pairs of tumors and corresponding matched adjacent normal tissues from NSCLC patients were examined by real-time PCR. The specific knockdown of ZFX by shRNA significantly inhibited cell viability and reduced colony formation of 95D cells. And ZFX silencing resulted in cell cycle arrest in G0/G1 phase. In addition, ZFX was overexpressed and correlated with lymph node metastasis in samples from 49 NSCLC patients. We reported for the first time that ZFX may play an important role in cell growth control and cell cycle progression of 95D cells. Furthermore, ZFX was overexpressed in samples of NSCLC and ZFX mRNA expression associated with lymph node metastasis. Therefore, our findings suggest that ZFX would be a potential target to development of therapies for NSCLC.