['This study was designed to assay the expression of zinc finger protein X-linked (ZFX) in renal cell carcinoma (RCC) tissues and evaluate the correlation between ZFX expression and prognosis of RCC patients.', 'The expressions of ZFX mRNA in 53 RCC tissues and 51 normal tissues were determined by quantitative real-time polymerase chain reaction (qRT-PCR). Immunohistochemistry (IHC) technology was used to measure the expression of ZFX protein. Then chi-square test was conducted to verify the association between ZFX expression and clinical parameters. Next, we explored the overall survival rate of RCC patients with Kaplan-Meier analysis. Finally, the correlation between ZFX expression and the prognosis of RCC patients was evaluated by Cox regression analysis.', 'The qRT-PCR result showed that the ZFX was significantly up-regulated in RCC tissues. As for the IHC consequence, the positive rate of ZFX expression in RCC specimens was 79.2%, while that in the normal control tissues was only 17.6%. Chi-square test showed that ZFX expression shared no close relationship with age, sex, or smoking (P>0.05), but was tightly associated with TNM stage, tumor size, and lymph node metastasis (P<0.05). Kaplan-Meier analysis showed that patients with ZFX positive expression had higher mortality than those with negative expression (P<0.05). Cox regression analysis revealed that ZFX expression had tight correlation with prognosis of RCC patients (HR=4.997, P=0.045, 95%CI=1.033-24.180).'] Is zFX a Strong Predictor of Poor Prognosis in Renal Cell Carcinoma?