Aim: An accurate estimation of the degree of prostate volume (PV) enlargement is important for the choice of treatment, and for prediction of treatment effect, the risk of acute urinary retention and the need for surgery. The purpose of this study was to evaluate the relationship PSA and PV in patients with histologically proven BPH. Material and Method: 248 men presented to lower urinary tract symptoms and were patologically proved to have benign prostatic hyperplasia by transrectal ultrasoun (TRUS) guided 14-core biopsy were evaluated in this study. Prostat volume was calculated by TRUS with the formula of an ellipsoid (PV= height x with x lenght x 0,52). Measurements of PSA (ng/ml). Serum PSA level was measured by One-Step Sandwich (Dual Mono) method using Beckman Coulter DX 1800 device. The patients evaluated in three groups according to their PV range (cohort of PV) (PV < 30 ml, PV: 30-60 ml, PV > 60 ml). The relationship between age and prostate volume and PSA levels were investigated the affact on these parameters. One way analyses of variance were used to test the difference among groups. The P value less than 0,05 was considered statistically significant. Results: The mean age was 66,97(+/- 1), mean PV was 57,58(+/- 4) ml, and mean serum PSA was 6,89(+/- 0,4) ng/ml. Fifty-seven percent of the patients have a serum PSA value greater than 4 ng/ml. Mean PSA and PV increased with each advancing cohort of age. The mean PSA values in the cohort of PV; PV < 30 ml, PV: 30-60 ml, and > 60 ml, were 2,69 +/- 0,2 ng/ml, 6,72 +/- 0,5 ng/ml, and 9,84 +/- 0,9 ng/ml, respectively (p< 0,01, p< 0,001). Discussion: There is no cut-off value of PSA in the estimation of prostate volume. In the absence of reliable direct measurement of PV or when it is not necessary to measure the exact volume of prostate, serum PSA determination may be used to designe of medical management for patients with BPH.