Introduction: Androgens are necessary for the development and functioning of the prostate gland. The association of serum testosterone and pituitary hormone levels with prostate cancer development is not completely understood. In this clinical study, we evaluated the role of serum testosterone, free testosterone, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels in predicting prostate cancer risk in patients who had transrectal ultrasonography-guided prostate biopsy with the suspicion of prostate cancer. Material and Methods: A total of 211 patients who were selected to undergo prostatic biopsy due to abnormal digital rectal examination and/ or a serum prostate-specific antigen (PSA) level > 2.5 ng/ ml were included in the study. The patient characteristics of total PSA, free/total PSA ratio, serum total testosterone, free testosterone, free/total testosterone ratio, FSH and LH levels were compared according to the pathological diagnosis. Results: The mean age was 63.91 years (range 44 - 83) and the mean PSA level was 9.23 ng/ml (range 0.13 - 50.41) in the whole group. Of 211 patients, 69 (32.7%) were positive for prostate cancer. The patients who were positive for prostate cancer had statistically lower levels of serum total testosterone compared with the patients who were diagnosed as having benign prostatic hyperplasia (BPH; 405 vs. 450.5 ng/dl, respectively; p = 0.013). The serum FSH level was significantly higher in men with prostatic cancer than in men with BPH (7.56 vs. 6.06 mIU/ml, respectively; p = 0.029). No significant differences between men with prostatic cancer and those with BPH were found for serum LH levels. When normal ranges for serum free and total testosterone levels were defined as 9 pg/ml and 300 ng/dl, respectively, patients who had low free testosterone and total testosterone levels had significantly higher cancer detection rates than patients with high serum androgen levels: 40.8% (40/ 98) versus 25.6% (29/ 113) (p = 0.021), and 48.6% (18/ 37) versus 29.3% (51/ 174), respectively (p = 0.023). After logistic regression analysis, none of the hormones showed a significant difference in predicting the risk of prostate cancer in patients undergoing prostate biopsy with suspicion of the disease. Conclusion: Our data suggest that patients diagnosed with prostate cancer have low levels of serum testosterone and high levels of serum FSH compared with the patients with BPH. No support was found for the theory that high levels of testosterone increase prostate cancer risk. Further studies are needed to clarify the relationship between hormones and prostate cancer etiology.