Objective: We evaluated learning retention in interns exposed to simulation. It was hypothesized that learning would degrade after 6 months and there would be a difference in retention between interns who played a critical role versus those who did not. Methods: A total of 23 groups of 5 to 9 interns underwent a cardiac scenario twice during 1 simulation experience and again 6 months later. We captured 69 recordings (23 before debrief at baseline [PrDV], 23 after debrief at baseline [PoDV], and 23 at 6-month follow-up [FUV]). Students were assigned different roles, including the critical role of ''doctor'' in a blinded, haphazard fashion. At 6-month follow-up, 12 interns who played the role of doctor initially were assigned that role again, while 11 interns who played noncritical roles initially were newly assigned to doctor. All videos of intern performance were scored independently and in a blinded fashion, by 3 judges using a 15-item check list. Results: Repeated-measures analysis of variance for interns completing all 3 time points indicated a significant difference between time points (F 2,22 ¼ 112, p ¼ .00). Contrasts showed a statistically significant difference between PrDV and PoDV (p ¼ .00), and PrDV and FUV (p ¼ .00), but no difference between PoDV and FUV (p ¼ .98). This was consistent with results including all data points. Checklist scores were more than double for PoDV recordings (16) 2-9 However, for health care education to improve patient safety and provide high quality management, learning retention is critical. 10 We were interested in assessing learning retention during simulation in health care education.Research supports the use of simulation to facilitate student learning, leadership, communication, and teamwork in an effort to reduce iatrogenic error.1 The systematic review of Harder 7 showed that self-reported confidence and competence scores increase when participants learn in simulation environments. The systematic review and meta-analysis of Cook et al 11 pooling the data from 35,226 participants indicated significant effects of simulation associated with knowledge, skills, and behaviors. Simulation has been effective in the development of some motor skills (eg, certain surgical procedures, pilot simulated training exercises, and manipulation skills). 10,12 However, data regarding actual learning retention and its objective measurement in a simulated environment remains limited. 7,13,14 In fact, of the 240,300 articles on simulation in the US National Library of Medicine, only 0.1% could be retrieved using the key words ''simulation and learning retention."According to Friedlander et al.,15 many key aspects of an effective learning paradigm, such as repetition, active engagement, stress, active involvement, and reinforcement, already have been incorporated into the simulation learning environment. Research indicates simulation to be realistic and effective. 16 Questions still exist, however, regarding how much learning is occurring and how generalizable this is, dependent on the rol...