Many international medical graduates (IMGs) enter North American residency programs every year. The Canadian IMG physician pool increasingly includes Canadian-born IMGs (C-IMGs) along with Immigrant-IMGs (I-IMGs). Similar trends exist in the United States. Our objective was to understand the similarities and differences in the challenges faced by both I-IMGs and C-IMGs during residency to identify actionable recommendations to support them during this critical time. We performed a multiple case study of IMGs' experiences at a large Canadian university. Within our two descriptive cases (I-IMGs, C-IMGs) we iteratively conducted twenty-two semi-structured interviews; we thematically analyzed our data within, between, and across both cases to understand challenges to IMGs' integration and opportunities for curricular innovations to facilitate their adaptation process. Research team members with different perspectives contributed reflexively to the thematic analysis. Participants identified key differences between medical culture and knowledge expected in Canada and the health systems and curricula in which they originally trained. I-IMG and C-IMG participants perceived two major challenges: discrimination because of negative labelling as IMGs and difficulties navigating their initial residency months. C-IMGs described a third challenge: frustration around the focus on the needs of I-IMGs. Participants from both groups identified two major opportunities: their desire to help other IMGs and a need for mentorship. I-IMGs and C-IMGs face diverse challenges during their training, including disorientation and discrimination. We identified specific objectives to inform the design of curriculum and support services that residency programs can offer trainees as well as important targets for resident education and faculty development.