Prostate cancer is the most important malignancy in men with advanced age. Oxidative stress contributes to the etiology and pathogenesis of the prostate cancer. The aim of this study was to determine the relation of antioxidant enzymes with the prostate cancer and to evaluate whether the activities of these enzymes were correlated with different stages and states with or without metastasis of disease. Moreover, we investigated oxidant-antioxidant state in prostate tissue with and without tumor. We also determined MnSOD expression by Western Blot analysis in the tissue protein extracts. One hundred sixty five men diagnosed with histologically confirmed prostate cancer were included in the study. The control group also consisted of 168 male subjects who were enrolled to Department of Urology for reasons other than lower urinary tract symptoms. Prostate cancer patients were histologically classified into two groups as low and high stage disease according to 2002 TNM classification. Moreover, tumors with Gleason score >7 were classified as poorly differentiated whereas those with Gleason score <7 were classified as well-differentiated tumors. The presence or absence of bone metastasis was determined by bone scanning of prostate cancer patients with serum PSA level> 10 ng/ml. Twenty one prostate cancer and adjacent non- tumorous specimens were resected with transurethral resection of prostate (TURP). Serum and prostate tissue malondialdehyde (MDA), total thiol (-SH) levels and SOD, GPx, CAT activities were determined spectrophotometrically. Western Blot analysis was performed for evaluating MnSOD protein expression. For the statistical analyses, Mann-Whitney U and Kruskal-Wallis tests were used where appropriate. Serum MDA levels, GPX and SOD activities were significantly higher and total -SH levels were significantly lower in patients with prostate cancer compared to those of the controls. Serum MDA levels were significantly increased in prostate cancer patients with high stage. Moreover, serum MDA levels were significantly elevated in bone metastasis group. However, serum total -SH levels and GPX activities were lower in bone metastasis group. We observed that total MDA levels and SOD activities were also higher in prostate tissues with tumor. GPX, CAT activities and total -SH levels were significantly lower in prostate tissues with tumor. Meanwhile, tumors had higher levels of MnSOD protein when the MnSOD protein expression was evaluated by Western analysis. In conclusion, we suggest that tissue GPX and CAT activities were decreased due to oxidative injuries in patients with prostate cancer and also increased MnSOD expression in cancerous tissue was to be an indicator for progression and stage of the disease.