The evaluation of medical students in the clinical setting (outside the classroom) is a great challenge due to the fact that the learning process becomes more complex. There is little scientific literature in which the research ends in an action to design efficient forms of evaluation. We aimed to design and validate an instrument to reach an evaluation by competencies in the Course: Introduction to Clinical Medicine at the National University of San Marcos (UNMSM) in Lima-Peru. This publication follows a research-action methodology, where the initial results led to the design of an evaluation methodology in clinical environments that is then re-evaluated again to determine if it really manages to evaluate the comprehensive skills required in a medical student. Results: 14 professors were interviewed. In the clinical environment, theoretical lectures and planned didactic sessions are used based on clinical cases. In clinical practice, the priority is given to clinical thinking, and problem-based learning (PBL). The reseach team in conjunction with the professors started the evaluation by competences process developing an evaluation instrument for the specific clinical practice. The participants observed resistance to the change because of certain administrative barriers y poor institutional support. The critical point in this investigation was the training in evaluation and learning methodologies. A training plan was required before starting their teaching activities. The professors agreed with the new form of evaluation and recognized the value of the teaching service with responsible and ethical dedication.