Introduction: the actions of nurses in Primary Health Care can help users to control and lose weight, as well as improving their eating habits and physical activity, impacting the daily routine of the whole family. Objective: to understand the role of nurses in prevention and in the control of obesity in Primary Health Care. Method: Phenomenological approach research performed with 12 nurses working in Basic Health Units in city of Minas Gerais. To obtain the testimonies, an interview was used with the following guiding questions: what have you done in relation to the prevention and control of the obesity in Basic Health Unit? What are your expectations regarding your performance against obesity? The organization and the analysis of the testimonies were carried out in accordance with the proposed by scholars of the social phenomenology of Alfred Schütz. Results: the Alfred Schütz social phenomenology made it possible to identify the typical of the nurse's action, the prevention and control of obesity in the context of Primary Health Care, as being the one that acts orienting healthy habits of life to the mothers of children, pregnant women and adults with chronic diseases and collectively in the oriented jogging and in the operative groups that exists in the health unit, with pregnant women and users with chronic diseases. Problems related to the unhealthy habits of the users' life and resistance to change of behavior, in addition to the limitations imposed by the service and the health team, are amenable to their actions. Their expectations include knowing the food profile and the weight of the population, performing specific groups for weight control, improving the articulation of the Basic Health Unit with other social facilities, acting with children and adolescents out of the Unit's space and receiving training to deal with obesity. Conclusion: it is believed that these nurses' performance characteristics provide support for the reflection about the way people are being cared for in this point of attention of the Health Care Network. In this sense, they can offer clues for the management of health services to promote the effective development of health policies, ensuring quality care for obese users.