Introduction: To enter a profession is to take on a new identity. Professional identity formation can be difficult, with medical learners struggling to adopt professional norms. The role of ideology in medical socialisation may offer insight into these tensions experienced by medical learners. Ideology is the system of ideas and representations that dominates the minds of individuals or social groups and calls individuals into certain ways of being and acting in the world. In this study, we use the concept of ideology to explore residents' experiences with identity struggle during residency. Methods: We conducted a qualitative exploration of residents in three specialties at three academic institutions in the United States. Participants engaged in a 1.5-hour session involving a rich picture drawing and one-on-one interview. Interview transcripts were coded and analysed iteratively, with developing themes compared concurrently to newly collected data. We met regularly to develop a theoretical framework to explain findings. Results: We identified three ways that ideology contributed to residents' identity struggle. First was the intensity of work and perceived expectations of perfectionism. Second were tensions between the developing professional identity and pre-existing personal identities. Many residents perceived messages regarding the subjugation of personal identities, including the feeling that being more than physicians was impossible. Third were instances where the imagined professional identity clashed with the reality of medical practice. Many residents described how their ideals misaligned with normative professional ideals, constraining their ability to align their practice and ideals. Conclusion: This study uncovers an ideology that shapes residents' developing professional identity—an ideology that creates struggle as it calls them in impossible, competing or even contradictory ways. As we uncover the hidden ideology of medicine, learners, educators and institutions can play a meaningful role in supporting identity development in medical learners through dismantling and rebuilding its damaging elements.