Background: The aim of this study was to compare the characterization of prostate cancer using the conventional and 2005 ISUP modified Gleason systems. Materials and Methods: The study employed samples from 40 prostate cancer patients with resection, biopsy and RP materials. The majority of cases (95%) comprised adenocarcinoma of the prostate with a modified combined Gleason score of 7 in 20 of the cases (50%). Results: Upgrading of Gleason scores to a score of 7 occurred in more than 45% of the cases. Conclusion: The study successfully showed that by the use of the 2005 ISUP modified Gleason system, score 6 cancers decreased from 25% to 17.5% of cases, whereas score 7 cancers increased from 45% to 50%.