Objective: to describe an on-call handover and presentation of clinical cases in the pediatrics service and its impact on learning in undergraduate medical interns. Methods: qualitative study with ethnographic approach, with the participation of undergraduate medical interns who rotated through the pediatrics service, during the bimonthly March-April 2019, and attending physicians who participated in the on-call handover. Observations, video recordings and interviews were carried out, subsequently an ethnographic analysis was performed. Results: during the on-call period, the presentation of clinical cases was identified as a formative activity; the intern physicians presented medical histories and admission notes prepared during the on-call period; the attending physicians participated actively through questions, comments, recommendations, and explanations that served as a guide for the students to achieve greater learning in professional competencies. Conclusion: the presentation of clinical cases during the on-call handover was a key formative activity in the development of two professional competencies in medical practice, diagnosis and treatment.