In many cancers, an increase in gene expression of DNMT3b has been reported. This enzyme inhibits the expression of many tumor suppressor genes through the methylation of the promoter sequence and plays a key role in the progression of cancer. In this study, the relationship between polymorphism rs406193 of this gene and the risk of prostate cancer in 60 samples was investigated. The results showed a significant association between genotype TT and the risk of prostate cancer (p=0.048). It is recommended that this study be repeated in larger populations and that the relationship between this polymorphism and gene expression be investigated.