INTRODUCTION AND OBJECTIVES: The first objective of this study was to assess percutaneous renal access (PCA) skills of urology Post-Graduate Trainees (PGTs) during Objective Structured Clinical Examination (OSCEs). The second objective was to determine whether previous experience with Percutaneous Nephrolithotomy (PCNL) improved performance. METHODS: After obtaining ethics approval, PGTs from two urology programs in Quebec between Post-Graduate Years (PGY-3 to PGY-5) were recruited. Each trainee was asked to answer a short questionnaire regarding previous experience in endourologic procedures. After a 3-minute orientation on the PERC Mentor™ simulator, each trainee was asked to perform task 4, where they had to correctly access all of the renal calyces and pop the balloons in a normal left kidney model. Data from the questionnaire and the performance report generated by the simulator were collected and analyzed. RESULTS: Thirteen PGTs participated in this study. PGTs had performed a median of 5 (0-50) laser prostatectomies, 50 (2-125) ureteroscopies, and 4 (0-50) PCNLs before this OSCE. When compared with PGTs without previous PCNL experience, PGTs with previous PCNL experience (8/13) performed significantly better in terms of shorter fluoroscopy time (FT) (10±1.5 vs. 5.1±0.7 min; p=0.04), fewer attempts required for successful puncture of the pelvi-calyceal system (PCS) (21±2.3 vs. 13±1.8; p=0.02), and had significantly lower complications in terms of fewer infundibular injury (7.4±1.5 vs. 2±0.4; p=0.004) and fewer PCS perforations (11±1.7 vs. 4.5±1.2; p=0.01). CONCLUSIONS: It is feasible to use the PERC Mentor™ simulator during OSCEs to assess PCA skills of urology PGTs. PGTs who had previous PCNL experience performed significantly better with fewer complications.