Purpose: The predicted shortage of primary care physicians emphasizes the need to increase the family medicine workforce. Therefore, Swiss universities develop clerkships in primary care physicians' private practices. The objective of this research was to explore the challenges,the stakes, and the difficulties of clinical teachers who supervised final year medical students in their primary care private practice during a 1-month pilot clerkship in Geneva. Methods: Data were collected via a focus group using a semistructured interview guide. Participants were asked about their role as a supervisor and their difficulties and positive experiences. The text of the focus group was transcribed and analyzed qualitatively, with a deductive and inductive approach. Results: The results show the nature of pressures felt by clinical teachers. First, participants experienced the difficulty of having dual roles: the more familiar one of clinician, and the new challenging one of teacher. Second, they felt compelled to fill the gap between the academic context and the private practice context. Clinical teachers were surprised by the extent of the adaptive load, cognitive load, and even the emotional load involved when supervising a trainee in their clinical practice. The context of this rotation demonstrated its utility and its relevance,because it allowed the students to improve their knowledge about the outpatient setting and to develop their professional autonomy and their maturity by taking on more clinical responsibilities. Conclusion: These findings show that future training programs will have to address the needs of clinical teachers as well as bridge the gap between students' academic training and the skills needed for outpatient care. Professionalizing the role of clinical teachers should contribute to reaching these goals. Keywords: clinical teacher, clinical teachers' training, clerkship in private clinical practice,supervision, primary care