RESUMEN
Background: Practice is essential in clinical training and can be carried out with simulations. The medical school of the University of Chile performs Objective Structured Clinical Examinations (OSCE) using standardized simulated patients for interns. Aim: To report the experience with OSCE in an environment with a high number of students. Material and Methods: Four hundred sixty-two students, participated in three OSCEs during 2016 and 2017, during their internal medicine clerkship. Each OSCE consisted of five scenarios of ambulatory care patients with prevalent medical conditions. Every student had to perform history taking, physical examination and deliver a diagnostic hypothesis, and a plan for management and counseling. Simulated patients provided feedback. To assess validity and reliability, in an argument-based model, planning and activity development were declared. The results were evaluated according to students' and organization variables, internal consistency, interobserver and theoretical concordance tests. Results: No significant bias was found by demographic features or evaluation moment. Internal consistency was good (Cronbach 0.8). Simulated patient evaluators had a high correlation with medical evaluators (r = 0.7). There was a low correlation between OSCE results and theoretical tests. Conclusions: OSCE's continuously assess competences during internal medicine clerkship in an environment with a high number of students.