BackgroundVirtual reality simulators are an integral part of modern surgical training and allow novice surgeons to acquire basic laparoscopic skills that are transferable to the operation room without compromising patient safety. The gold standard training method is proficiency-based training, where all trainees practice until a pre-defined proficiency level is reached. Simulator software versions are regularly updated to increase the quality of the simulator experience, but the impact of software updates used in conjunction with existing proficiency levels is unknown. MethodsTwenty surgical novices were randomized to simulator training on the LapSim® virtual reality simulator using either a 2019-version (new software group) or a 2016-version (old software group) of the simulator software. All participants practiced until reaching the proficiency level established for the old software. After 3-5 weeks, all participants returned and practiced to proficiency again using the old software. ResultsThe mean time to proficiency for the new software group was 183 minutes (SD: 43) versus 285 minutes (SD: 26) for the old software group (p<0.001). During the follow-up test, participants from the new software group spent 189 minutes (SD: 61) versus 91 minutes (SD: 50) (p=0.001) for the old software group to reach proficiency again. ConclusionUpdating simulator software without updating the proficiency levels creates the risk of changing the amount of training necessary to reach proficiency. Updates of simulator software for virtual reality simulators must lead to a critical re-evaluation of the previously established proficiency levels to ensure optimal outcomes of simulation-based training.