Background: Cytotoxic T-lymphocyte antigen 4 (CTLA-4), the T cell surface antigen is expressed during activation. Prostate cancer (PCa) is one of the most common cancers in Western population and its rate is increasing in the Eastern World. The aim of this study was to evaluate cytotoxic T lymphocyte associated antigen-4 (CTLA-4) gene+49A/G polymorphisms in prostate cancer patients. Material and methods:This study included 119 (mean age: 68.94±8.38 years) healthy controls and 62 (mean age: 72.83±7.60 years) patients with prostate cancer. The CTLA-4 gene+49A/G (rs231775) gene regions were amplified using polymerase chain reaction (PCR), detected by restriction fragment length polymorphism (RFLP).