Prostate gland is a walnut sized organ located between the bladder and the penis. Prostate specific antigen (PSA) is a protein produced by normal, as well as malignant cells of the prostate gland. The PSA test measures the level of PSA in a man’s blood. This study was aimed at investigating the assessment of prostate specific antigen (PSA) in prostrate disorders. Study was carried out on a total of 80 patients attending clinic and laboratory investigations from Achunike Hospital and St. Cyprian Hospital referred to Queens medical laboratories for prostate specific antigen assay. Subjects were divided into four groups (A, B, C and D) their ages between 40 to 80 years. Group A is the control group. This group comprises apparently healthy individuals who have no history of prostate disorder. Group B consists of subjects with Prostatitis. Group C and Group D are patients with Benign prostate hyperplasia and prostate cancer respectively. Blood samples were collected venous in a plain sterile tube, allowed to clot and serum sample separated for PSA assay using Enzyme linked Immunosorbent assay technique. The result of this study showed no significant (p > 0.05) change in PSA levels in group B diagnosed with prostatitis with mean values (2.84 ± 1.27). However, there was significant increase (P < 0.05) in PSA levels in subjects with Benign prostate hyperplasia (BPH) (14.11 ± 4.88) .The result of PSA levels in prostate cancer patients showed marked increase in PSA levels (19.64 ± 5.22) compared with control and also a remarkably higher PSA values compared with B and C (p < 0.05). Therefore this research work has shown that prostate specific antigen is elevated in both benign prostate hyperplasia and prostate cancer. It has also identified PSA as an important marker in differentiating prostate disorders caused by BPH and prostate cancer from disorders caused by prostatitis. Keywords: Prostate Specific Antigen, Prostatitis, Benign Prostate Hyperplasia and Prostate Cancer.