Objectives: The main objectives of this study were to examine the concordance of the Gleason score after biopsy and after radical prostatectomy, and to examine the connection between values of preoperative parameters with the change of Gleason score in the samples after radical prostatectomy. Study Design: A cross–sectional study with historical data. Participants and methods: The study was conducted on 44 patients of the Department of Urology, University Hospital Center Osijek, who underwent radical prostatectomy within two years, from January 1st, 2017 until January 1st, 2019. The Gleason scores before and after radical prostatectomy were obtained from hospital documentation of the Department of Urology, University Hospital Center Osijek, as well as the relevant characteristics and clinical parameters of patients who underwent radical prostatectomy. Results: In 64% of patients, the Gleason score matched in samples taken after biopsy and after radical prostatectomy, while in 36% of patients there was a change in the score. In 15 patients there was an increase in the Gleason score after prostatectomy, while in only one patient a lower Gleason score was recorded after prostatectomy. Significantly more patients with Gleason 3 + 4 and Gleason 4 + 3 score were observed in the samples after radical prostatectomy than in the samples after biopsy. No association was observed between age, PSA, PSAD, prostate volume, number of positive samples, and pathological stage with changes in Gleason score after radical prostatectomy. Conclusion: There is a statistically significant difference in the Gleason score before and after radical prostatectomy, while no statistically significant association of preoperative variables with the change in the Gleason score was observed.