The results showed an association of the AC and CC genotypes of IL-18 −607 with a significant decrease in the risk of RCC compared with the AA genotype (odds ratio (OR) = 0.44 and 0.35, 95% confidence interval (CI) = 0.27–0.72 and 0.18–0.66, p = 0.0008 and 0.0010, respectively). The gene discussed is IL18; the disease is renal cell carcinoma.