To determine diagnostic yield and MR imaging predictors of prostate cancer (PC) detection on MR guided prostate biopsy (MRgBx).A HIPAA-compliant, IRB approved retrospective study of 108 men with history of negative or GS6 prostate cancer on prior biopsies but persistently elevated PSA were performed. Patients underwent diagnostic multiparametric 3T prostate MRI followed by MR guided prostate biopsy. Clinical, imaging and pathological information were collected. Upgrading was defined by an increase Gleason score on MRgBx compared to prior TRUSBx. Mann-Whitney test was used for continuous variables, Chi2 test were used for categorical variables.Of the 108 patients, 24 (22.2%) had elevated PSA and no prior biopsy, 35 (32.4%) had elevated PSA with prior negative biopsy, and 49 (45.4%) had known history of low grade prostate cancer. Prostate cancer was detected in 63/108 (58.3%) of the patients. Per MR biopsy target, the diagnostic yield of targeted biopsy per target was 73/138 (52.9%). Of the targeted biopsies that were performed, 23 (60.7%) had Gleason 3+3, 26 (18.8%) had Gleason 3+4, 10 (7.2%) had Gleason 4+3, and 14 (10.1%) had Gleason 8-10. There was 1 (0.9%) major complication (urosepsis). The diagnostic yield of target lesion based on overall PiRADS score were as follow: overall PiRADS score 1 was 1/3 (33.3%), PiRADS 2 was 0/6 (0%), PiRADS 3 was 15/54 (27.8%), PiRADS 4 was 39/55 (70.9%), and PiRADS 5 was 17/18 (84.4%). In patients who had prior TRUS biopsy (n = 40), 15/40 (37.5 %) of the patients were upgraded to a higher Gleason score. The sensitivity, specificity, PPV, NPV and accuracy for overall score of 4 or 5 for positive MRgBx was 77.8%, 73.4%, 76.7%, 74.6%, and 75.7%. Compared to negative targeted biopsy, positive targeted biopsy had lower ADC (1105 vs 975, P <0.01), larger MRI diameter (1.2 cm vs cm 1.4, P= 0.01), smaller prostate volume (66 vs 41, P < 0.01), higher proportion of overall PiRADS score of 4/5 (26.5 vs 77.8%, P <0.01), DWI score 4/5 (25.0% vs 70.8%, P < 0.01), and T2 score 4/5 (21.9 vs 65.3%, P <0.01), respectively.MRgBx yielded a Gleason upgrading in 37.5% of the patients with prior GS6 biopsy tumors. Overall diagnostic yield of MRI guided prostate biopsy was 58.3%. Men with positive MRgBx had tumors which were larger in size, lower ADC value, and higher T2, DWI and overall score compared to men with negative MRgBx. PiRADS reporting is an accurate measure to predict positive MR guided biopsy targets.