Background and Objective: Today's, the Gleason grading system is well known as the world's most commonly used histological system for prostate cancer. It provides significant information about the prognosis. This prospective paper assessed the correlation of transrectal ultrasound (TRUS) guided biopsy and radical prostatectomy specimens in terms of Gleason scores. In this matter, the effect of PSA density (PSAD) and prostate size on the Gleason scores were explored.Methods: This paper is conducted as a prospective study in which the medical records, comprised the pathology reports, of 68 patients with prostate cancer who underwent radical retropubic prostatectomy. Then, the preoperative Gleason score was compared to the Gleason score of the prostatectomy specimen.Results: Patients age ranged from 59 to 79 years, in which the median was 64 years. The comparison of the Gleason scores from the biopsy and radical prostatectomy specimens revealed that it was only identical in 24 out of 68 (35.3%) cases. On the other hand, the mean Gleason score obtained from the TURS biopsy was 6.4, compared with a mean score of 7.1 on the radical prostatectomy specimens. Meanwhile, there was a significant difference between Gleason scores (P<0.001). The experimental results confirmed that PSAD in 0.195, 0.22, 0.23, 0.25 cut of points had both high specificity and sensitivity for concordance of TRUS biopsy result using the Radical prostatectomy. Conclusion:This study provides evidence that the Gleason scores of the needle prostate biopsies and those of the radical prostatectomy specimens were concordant in some cut off points of PSAD especially between 0.195 -0.28. Therefore, it has seemed that PSAD can be a proper scale to determine the concordance of TRUS biopsy result using the Radical prostatectomy.