Objective: To investigate the correlation between the PI-RADS score and the pathologic Gleason score in the final pathological grading and to detect risk factors associated with the outcomes. Materials and Methods: Data from January 2017 to September 2019 were reviewed. Inclusion criteria included patients who had undergone standard protocol prostate magnetic resonance imaging (MRI) in King Chulalongkorn Memorial Hospital and underwent radical prostatectomy during the period. Data collected were age, PI-RADS score, Gleason score (GS), prostate-specific antigen (PSA), prostate size, PSA density, lesion size, and extraprostatic extension (EPE) evident in MRI. Results: One hundred and eight patients were included. PI-RADS was significantly associated with GS (Chi-Square p = 0.039). The percentage of significant tumors found in PI-RADS 3, 4, 5 were 66%, 86% 90% respectively. Analysis of independent risk factors only found PI-RADS 5 to have a statistically significant association with GS ≥ 7 (OR6.67 (1.24-35.71) p = 0.03). The cut-off value of lesion size ≥ 15 vs < 15 and PI-RADS 4 had a higher odds ratio than other parameters (OR 3.89 (0.82-18.41) p = 0.09, OR 3.29 (0.79-13.86) p = 0.11 respectively). Conclusion: The PI-RADS scoring system was found to be highly associated with Gleason’s grading score. No association was found between any significant risk factor and significant prostate cancer. Lesion size could be used to combine with the PI-RADS scoring system in the detection of significant tumors. A high percentage of significant tumors were found with a PI-RADS 3 score and it may be worth taking a biopsy in the case of a PI-RADS 3 lesion.