Introduction Rapid-cycle deliberate practice (RCDP) is a simulation-based educational strategy that consists of repeating a simulation scenario a number of times to acquire a planned competency. When the objective of a cycle is achieved, a new cycle initiates with increased skill complexity. There have been no previous randomized studies comparing after-event debriefing clinical manikin-based simulation to RCDP in adult cardiopulmonary resuscitation (CPR). Methods We invited physicians from the post-graduate program on Emergency Medicine of the Hospital Israelita Albert Einstein. Groups were randomized 1:1 to RCDP or after-event debriefing simulation prior to the first station of CPR training. During the first 5 min of the pre-intervention scenario, both groups participated in a simulated case of an out-of-hospital cardiac arrest without facilitator interference; after the first 5 min, each scenario was then facilitated according to group allocation (RCDP or after-event debriefing). In a second scenario of CPR later in the day with the same participants, there was no facilitator intervention, and the planned outcomes were evaluated. The primary outcome was the chest compression fraction during CPR in the post-intervention scenario. Secondary outcomes comprised time for recognition of the cardiac arrest, time for first verbalization of the cardiac arrest initial rhythm, time for first defibrillation, and mean pre-defibrillation pause. Results We analyzed data of three courses conducted between June 2018 and July 2019, with 76 participants divided into 9 teams. Each team had a median of 8 participants. In the post-intervention scenario, the RCDP teams had a significantly higher chest compression fraction than the after-event debriefing group (80.0% vs 63.6%; p = 0.036). The RCDP group also demonstrated a significantly lower time between recognition of the rhythm and defibrillation (6 vs 25 s; p value = 0.036). Conclusion RCDP simulation strategy is associated with significantly higher manikin chest compression fraction during CPR when compared to an after-event debriefing simulation.