Data from the Brazilian Ministry of Health shows that the breast cancer is one of the leading causes of women's death, despite the enhancements in treatment and diagnosis of this disease. Successive explanatory advertising campaigns emphasized the methods available for prevention: auto examination, clinical examination by a health care professional and mammography. Regardless of their relevance, only these strategies did not reduced incidence of breast cancer, since they do not impact on the oncogenesis factors. The objective of this article is to develop a health promotion activity through the reinforcement of the previous knowledge and aggregation of new information about breast cancer of a basic health unit. The methodology used was a transversal study of pedagogical intervention in the waiting rooms of a basic health unit. The pedagogical intervention was composed by an interactive questionnaire, lecture and discussion about the topic associated with a qualitative and quantitative evaluation of the activity. The proposed activity had positive results since the participants had qualitative and quantitative improvement in their knowledge and also a good interactivity with the researchers.