Background: Endoscopic retrograde cholangiography (ERCP) is a challenging procedure with considerable risk. Computerized simulators are valuable in training for flexible endoscopy, but little data exist for their use in ERCP training.Aim: To determine a simulator's ability to assess the level of ERCP skill and its responsiveness over time to increasing trainee experience.Materials and Methods: In this prospective parallel-arm cohort study, six novice gastroenterology fellows and four gastroenterology faculty with expertise in ERCP completed four simulated baseline cases and the same four cases at a later date. This study took place at a surgical skills center at an academic tertiary referral center. The primary outcome was the total time to complete the ERCP procedure.Results: For the baseline session, experts had a shorter total procedure time than novices (444.0 vs. 616.9 s; least squares mean; p = 0.026). There was no significant difference between experts and novices in the difference of total procedure time between session 1 and session 2 (-200.3 vs. -164.4; least squares mean; p = 0.402).Conclusions: The simulator was able to differentiate experts from novices for the primary outcome of total procedure time. The simulator was not responsive to an increase in trainee experience over time. [ABSTRACT FROM AUTHOR]