Recent studies have indicated that the prostate-specific antigen (PSA) gene polymorphisms may be associated with the risk of prostate cancer in Caucasian populations. To verify the association, we examined the PSA polymorphisms at positions -158 and -252 in 300 prostate cancer cases, 216 benign prostatic hyperplasia (BPH) cases, and 266 controls by the PCR-restriction fragment length polymorphism analysis. Regarding the PSA polymorphism at position -158, the A allele was less common in the Japanese population (A 0.22, G 0.78) than that in other ethnic populations (A 0.37-0.52, G 0.48-0.63). No significant associations were found between the polymorphism and the risks of prostate cancer (P=0.530) and BPH (P=0.740) and between the polymorphism and the serum PSA level (P=0.626). As for the polymorphism at position -252, no significant results were also found. In conclusion, the PSA polymorphisms may not be associated with the risk of prostate cancer development and its disease progression and the risk of BPH in Japanese men, and may also be not related to the serum PSA level in Japanese men with prostate cancer.