Introduction. The use of human patient simulators is an effective strategy in the teaching of clinical procedures. However, there is little information to help teachers improve their teaching strategies, allowing them to improve learning experiences according to the age or sex of students who use this type of simulation. Objectives. To identify if there are differences by sex or age in association with the skills of the students of the first semester of medicine for phlebotomy. Design. Quasiexperimental. Places. Medical Simulation Centre Montagne of the Marista University of Merida. Participants. First semester medical students. Interventions. Educational intervention of the phlebotomy process with sample taking, and using high fidelity simulators. For the analysis, sociodemographic variables were associated with the performance of the students. Main result measures. The practical and th...