The University of Sao Paulo School of Nursing (EEUSP) went through a period of transition from undergraduate syllabus between the years 2009 and 2010. This change was made to integrate basic and clinical cycles and to reduce fragmentation of the disciplines. The mental health nursing education was included in many modules including the primary care. This qualitative study aimed to identify how the service offered to people with mental illness was performed by 20 undergraduate students in the context of primary care and how they were prepared. Data collection was conducted through semi-structured interviews, in August 2012, in EEUSP After thematic analysis, we separated in categories: Teaching-learning process, Basic Health Unit and Mental health-illness process. The socially constructed conception of madness added to the problems related to academic training may result in lack of preparation in nursing mental health care.