International audienceImportance Evidence is scarce on the effectiveness of simulation-based training in transesophageal echocardiography (TEE).Objective To assess the effectiveness of simulation-based teaching vs traditional teaching of TEE knowledge and skills of cardiology fellows.Design, Setting, and Participants Between November 2020 and November 2021, all consecutive cardiology fellows inexperienced in TEE from 42 French university centers were randomized (1:1; n = 324) into 2 groups with or without simulation support.Main Outcomes and Measures The co-primary outcomes were the scores in the final theoretical and practical tests 3 months after the training. TEE duration and the fellows’ self-assessment of their proficiency were als...