ABSTRACT Teaching is an essential skill for future doctors. Peer-assisted learning (PAL)–where students take up a teaching role at an early stage of their training–is widely used in medical curricula. No studies have explored the long-term perceived impact of peer teaching. Therefore, we aimed to determine how former peer teachers reflected on PAL and its perceived long-term impact. In this longitudinal descriptive study, we conducted 42 semi-structured interviews with 11 former peer teachers at the University of Antwerp. Five of them were interviewed 6 months after PAL; 6 of them 9 years after PAL. This latter group was also interviewed during PAL in a previous study. We conducted secondary analyses of previously collected interviews, consistently comparing the findings with new data gathered from the current interviews. Using realist thematic analysis, topic summary themes were generated. Former peer teachers reflected on their PAL experience with a lot of satisfaction. Those meanwhile working as residents are still passionate about teaching. Peer teachers experienced a gain in clinical examination- and professional skills in the long-term, facilitating a smoother transition to their internship. Our findings suggest that PAL selects diverse but committed students. The longitudinal data demonstrate how PAL initiates or stimulates different skills in diverse students, including public speaking, teaching, time management, and self-efficacy in specific clinical skills. Regarding the chicken-and-egg question, our study encompasses both longitudinal cases illustrating the pre-existing skill theory and cases demonstrating how achieved competences were induced by PAL. Former peer teachers experienced long-term benefits of PAL, which eased their transition into the internship. PAL has the potential to ignite a lasting passion for teaching, providing diverse and unique learning opportunities not only for the most talented and ‘pre-selected’ medical students but also for a range of dedicated future clinicians.