Background: The risk stratification of prostate cancer using Gleason grade group (GG), serum prostate-specific antigen (PSA), and T staging has an important role for appropriate treatment. In fact, the GG of biopsy was not the same as the prostatectomy specimen. The upgrading of GG has a significant risk of delay treatment. The study aims to evaluate the concordance of GG between biopsy and prostatectomy specimens and the factors of upgrading GG. Materials and Methods: Retrospectively reviewed data from January 2010 to December 2019, 137 patients underwent prostate biopsy and followed by prostatectomy. Patients’ data include pathological reports, imaging reports, serum PSA, PSA density (PSAD), and free PSA were analyzed by univariate and multivariate analysis. Results: The concordance between the pathology was found in 54 specimens (39.4%) with the upgrading of GG in the prostatectomy was 57 specimens (41.6%). Furthermore, the downgrading was 26 specimens (18.9%). Serum PSA >10 ng/ml (P 0.003), PSAD >0.2 ng/ml/cm3 (P 0.002), free/total PSA ratio (P 0.003), margin positive for malignancy (P 0.033), and extraprostatic involvement (P 0.039) were significantly related with upgrading at the univariate analysis. Only a PSAD >0.2 (P 0.014) was found to be an independent factor that is predictive of upstaging in multivariate analysis. Conclusions: The prevalence of upgrading of GG from prostate biopsy to radical prostatectomy is as high as the other study. The factor that related to upstaging of GG was PSAD. Therefore, additional tools for biopsy were required to enhance the accurate diagnosis and staging of prostate cancer.