The exercise of preceptorship has been a reality based on the changes resulting from the government policy of training health professionals with a focus on the principles and demands of the Unified Health System. After ten years of curricular reform there was a need to understand the strengths and weaknesses in the effectiveness Teaching-Service Integration. Objectives: To understand the motivations for adherence, permanence and evasion to the exercise of preceptorship. Methods: Qualitative case study. Seventeen preceptors were interviewed in Basic Family Health Units about the experience in the exercise of preceptorship, covering institutional responsibilities, factors determining adherence, permanence or giving up the role of preceptor. The speeches were analyzed using the Iramuteq software. Results: The research revealed as factors that hinder the adherence and permanence of the preceptors the fragility in the management of the teaching-service integration, interference of the liberal hegemonic model of health work in the preceptorship practice; precariousness of services; lack of pedagogical training policy and institutional and financial incentives. Conclusions: There is a need for official recognition of the role of preceptor by the academy and service, redimensioning the importance of internships in family health for medical training.