Rates among females are generally about half of those among males. Though few risk factors are established for RCC, there are a number of predisposing conditions which are known to be related to the development of RCC, such as cigarette smoking, obesity, hypertension, diabetes, family history of cancer, and others. However, only a part of the individuals exposed to these risk factors will develop RCC in their life time, suggesting that individual differences including genetic susceptibility factors may be one of the most critical agents in renal cell carcinogenesis. MicroRNAs are a class of endogenous, small and non-coding RNAs, which are initially transcribed from genomic DNA to long primary transcripts and then are cleaved by nuclear Drosha into 60–70 nt hairpin-shaped precursor RNAs. Pre-miRNAs are exported to the cytoplasm by Exportin-5 and are further processed into,22 nt mature miRNA duplexes by the cleavage of Dicer. In association with RNA-induced silencing complex, miRNAs can induce mRNA degradation or translational repression by binding to the 39-untranslated region of their target genes at the posttranscriptional level. To date, it has been estimated that miRNAs modulate the expression of approximately 30% of human genes. MiRNAs are involved in a wide range of biological processes including cell cycle regulation, apoptosis and stem cell maintenance, development, metabolism and aging. It has been shown that miRNAs participate in human carcinogenesis as either tumor suppressors or oncogenes. Accumulative studies have suggested that single nucleotide polymorphisms or mutations could make a significant contribution to disease susceptibility and outcome. Genetic variants or mutations in miRNAs or pre-miRNAs may alter miRNA expression and/or maturation. One study has systematically identified 323 SNP in 227 known human miRNAs, and 12 SNPs are located within the miRNA precursors. The SNP rs895819 is located at the loop of premiR-27a and involves an A.G nucleotide transition. Sun et al. Temozolomide reported the polymorphism could lead to process variation, higher expression of miR-27a and eventually predisposition of gastric cancer. While Yang et al. found that G allele of rs895819 might impair the maturation of the miR-27a, thus, was associated with reduced familial breast cancer risk. Moreover, MertensTalcott et al. reported that in breast cancer cells, transfection of antisense miR-27a lead to increased expression of Zinc finger and BTB domain containing 10 and these responses were accompanied by decreased expression of Sp-dependent survival and angiogenic genes, including survivin, vascular endothelial growth factor, and VEGF receptor 1. However, over-expression of survivin was frequently observed in different types of cancer, including RCC. To date, there is no study on the association between pre-miR27a polymorphism and RCC susceptibility. Based on our knowledge regarding the new polymorphism and biological function of miR-27a, we hypothesized that the pre-miR27a polymorphism was associated with RCC susceptibility. To test this hypothesis, control study in a Chinese population. Nowadays, increasing studies have suggested that miRNAs, which play an important role in cancer progress as tumor oncogenes or tumor suppressors are involved in crucial biological processes, including development, differentiation, apoptosis and proliferation. Genetic variations in miRNAs have been reported to be related with many tumors, such as breast cancer, gastric cancer, colorectal cancer.