Purpose: To investigate validity evidence for a simulator-based test in robot-assisted radical prostatectomy (RARP). Materials and Methods: The test consisted of three modules on the RobotiX Mentor VR-simulator: Bladder Neck Dissection, Neurovascular Bundle Dissection, and Ureterovesical Anastomosis. Validity evidence was investigated by using Messick's framework by including doctors with different RARP experience: novices (who had assisted for RARP), intermediates (robotic surgeons, but not RARP surgeons), or experienced (RARP surgeons). The simulator metrics were analyzed, and Cronbach's alpha and generalizability theory were used to explore reliability. Intergroup comparisons were done with mixed-model, repeated measurement analysis of variance and the correlation between the number of robotic procedures and the mean test score were examined. A pass/fail score was established by using the contrasting groups' method. Results: Ten novices, 11 intermediates, and 6 experienced RARP surgeons were included. Six metrics could discriminate between groups and showed acceptable internal consistency reliability, Cronbach's alpha = 0.49, p < 0.001. Test-retest reliability was 0.75, 0.85, and 0.90 for one, two, and three repetitions of tests, respectively. Six metrics were combined into a simulator score that could discriminate between all three groups, p = 0.002, p < 0.001, and p = 0.029 for novices vs intermediates, novices vs experienced, and intermediates vs experienced, respectively. Total number of robotic operations and the mean score of the three repetitions were significantly correlated, Pearson's r = 0.74, p < 0.001. Conclusion: This study provides validity evidence for a simulator-based test in RARP. We determined a pass/fail level that can be used to ensure competency before proceeding to supervised clinical training.