Introduction: Task interruptions are reportedly frequent disturbances for emergency physicians performing advanced life support (ALS). The aim of this study was to evaluate the benefit of adding task interruptions in ALS simulated training session. Methods: We conducted a multi centered randomized controlled trial in four emergency departments of a university hospital in Paris, France. Each emergency team included one resident, one nurse and one emergency physician. The teams were randomized for the nature of their training session: control (without interruption) or realistic (with interruptions). The interruption consisted of an interfering family member speaking a foreign language, and of repetitive phone calls during ALS. After the first training session, teams were evaluated on a second realistic session with task interruptions. The primary outcome was non-technical skills assessed with the TEAM score during this evaluation session. We also measured the no flow time, and the Cardiff score, which reflects the quality of ALS: including chest compression depth and rate, no flow time. Results: On a total of 23 included teams, 12 had a control training session and 11 with task interruptions. Baseline characteristics and TEAM score were similar between the two groups (Mean difference: 3,3 [-2,2; 8,9]; p = 0,26). During the evaluation session, the TEAM score was lower for “realistic” teams (mean difference -8 [95% confidence interval -13; -3]). We also report a higher no flow time and similar overall Cardiff score. Conclusion: In this simulated ALS study, the presence of disturbances during simulation seemed to worsen the quality of training. This study highlights the negative consequences of task interruptions in emergency medicine.