PSA (Prostate Specific Antigen), a serine protease, is secreted by the prostate gland epithelial cells. TPSA (Total PSA), which can be immune detected, includes free PSA & PSA-ACT complex. In males, PSA screening can be used as one of the diagnostic indexes of early prostate cancer. Raised PSA levels are associated with prostate disease, including prostatitis, benign prostatic hyperplasia (BPH) & prostate cancer (PCa). Patients with BPH have a significantly higher percentage of free PSA than patients with PCa. Therefore, the FPSA/TPSA ratio can be used in the differential diagnosis between prostate cancer & benign prostatic hyperplasia. The determination of PSA & fPSA levels are recognised as an important measurement in the assessment of prostate cancer.