The mouse double minute 2 (MDM2) gene plays a key role in the p53 pathway, and the SNP 309T/G singlenucleotidepolymorphism in the promoter region of MDM2 has been shown to be associated with increased riskof cancer. However, no consistent results were found concerning the relationships between the polymorphismand prostate cancer risk. This meta-analysis, covering 4 independent case-control studies, was conducted tobetter understand the association between MDM2-SNP T309G and prostate cancer risk focusing on overall andsubgroup aspects. The analysis revealed, no matter what kind of genetic model was used, no significant associationbetween MDM2-SNP T309G and prostate cancer risk in overall analysis (GT/TT: OR = 0.84, 95%CI = 0.60-1.19;GG/TT: OR = 0.69, 95%CI = 0.43-1.11; dominant model: OR = 0.81, 95%CI= 0.58-1.13; recessive model: OR =1.23, 95%CI = 0.95-1.59). In subgroup analysis, the polymorphism seemed more likely to be a protective factorin Europeans (GG/TT: OR = 0.52, 95%CI = 0.31-0.87; recessive model: OR = 0.58, 95%CI = 0.36-0.95) thanin Asian populations, and a protective effect of the polymorphism was also seen in hospital-based studies in allmodels (GT/TT: OR = 0.74, 95%CI = 0.57-0.97; GG/TT: OR = 0.55, 95%CI = 0.38-0.79; dominant model: OR= 0.69, 95%CI = 0.54-0.89; recessive model: OR = 0.70, 95%CI = 0.51-0.97). However, more primary studieswith a larger number of samples are required to confirm our findings.