Measurement of the serum levels of PSA by ELISA method showed that the mean serum levels of PSA were as follows: 28.20 ± 3.46 ng/ml (range 5.90–121.0 ng/ml, in patients with metastatic prostate cancer), 18.48 ± 2.28 ng/ml (range 4.50–112.0 ng/ml, in patients with localized prostate cancer), 7.93 ± 3.71 ng/ml (range 1.27–20.5 ng/ml, in patients with BPH), and 1.42 ± 0.72 ng/ml (range 0.5–2.5 ng/ml, in healthy subjects). This evidence concerns the gene KLK3 and benign prostatic hyperplasia.