Background: The current selection criteria to AS is critical and it becomes even more relevant in Latin America, given the higher proportion of high risk cancers. The objective of this study is to analyze the accuracy of mpMRI using PI-RADS v2 in predicting the risk of upgrading on re-biopsy (UR) in men with low-risk PCa on AS. Methods: In this Institutional Review Board approved prospective study, patients with low-grade PCa selected for AS at our institution underwent mpMRI at least 6 weeks after the baseline 12-core random prostate biopsy (BSB), from March 2014 to March 2016. One blinded abdominal radiologist evaluated the exams regarding presence of dominant lesion and assigned the PI-RADS v2 score. MRI-target transrectal ultrasound-guided re-biopsies were performed in all patients within 6-12 months after the BSB. Standardized 12-core biopsy was performed and additional cores were taken from suspicious areas on mpMRI. Results: One hundred and nine patients were included, 93 (85.3%) patients had a dominant lesion on MRI. mpMRI were classified as PI-RADS 1, 2 or 3 in 67 (61.5%) patients, and as PI-RADS 4 or 5 in 42 (38.5%) patients. UR occurred in 42 (38.5%) patients. Out of these, 39 (92.8%) had radical prostatectomy, 6 (15.4%) T2a, 24 (61.5%) T2b, and 9 (23.1%) T3a. The diagnostic performance of mpMRI for PCa upgrading after re-biopsy was summarized in table 1. Patients assigned as PI-RADS 4 or 5 presented a significantly higher risk for UR compared with patients with PI-RADS 1, 2 or 3 (73.8% vs 16.4%, p < 0.001). Logistic regression analyses demonstrated that PI-RADS 4 or 5 remained a significant predictor of UR (OR: 37.366, p < 0.0001). Conclusions: We demonstrated in our population that mpMRI using PI-RADS v2 is a significant predictor for upgrading on re-biopsy in patients on AS and could be used to guide TRUS biopsy, increasing the accuracy of current clinical criteria for AS.