Increased expression of CARMA3 has been reported to be involved in tumorigenesis and tumor progression of several cancer types. The aim of our study is to investigate the prognostic role of CARMA3 expression in patients with renal cell carcinoma (RCC). Real-time quantitative PCR was performed to detect CARMA3 mRNA expression level in 31 paired samples of RCC and adjacent noncancerous renal tissues. Subsequently, extensive immunohistochemistry was performed to detect CARMA3 protein expression in 114 RCC cases. Clinicopathological data for these patients were evaluated. The prognostic significance was assessed using the Kaplan-Meier survival estimates and log-rank tests. CARMA3 mRNA expression was significantly higher in RCC tissues compared with adjacent noncancerous renal tissues (3.525 +/- 1.233 vs. 1.512 +/- 0.784, P < 0.001). In addition, high CARMA3 expression in RCC tissues was significantly associated with tumor size (P = 0.026), histological differentiation (P = 0.039), tumor stage (P = 0.006), and the presence of metastasis (P < 0.001). Moreover, Kaplan-Meier analysis showed that patients with high CARMA3 expression also had a significantly poorer prognosis than those with low CARMA3 expression (log-rank test, P < 0.001). Furthermore, multivariate analysis illustrated that CARMA3 overexpression might be an independent prognostic indicator for the survival of patients with RCC. In conclusion, this work shows that CARMA3 may serve as a novel and prognostic marker for RCC and play a role during the development and progression of the disease.