Introduction : Prostatic specific antigen (PSA) has achieved a wide spread clinical use as a tumour marker in the field of prostatic pathology. In the present study PSA was determined in patients of benign prostate hypertrophy (BPH) and Carcinoma Prostate (Ca–P) to evaluate its diagnostic efficiency in day to day management of prostate cancer patients. Maerial and methods : This observational study was carried out in RIMS, Ranchi, Department of General surgery over a period of 1 year. 40 patients admitted through outdoor, emergency presenting with features of Lower Urinary Tract Symptoms (LUTS) were included in the study. Result : 90.9% of the patients with PSA value >10ng/ml have Ca–P with specificity and positive predictive value of PSA at >10ng/ml being 83.3% and 86.9% respectively. Conclusion : Though PSA is not a specific investigation for diagnosis of Ca–P but higher values of PSA is more likely due Ca–P. Positive test does not mean to have prostate cancer nor does a negative test always confirms the absence of cancer.