The purpose of this study is to understand marginalisation in class because of language use in English-medium instruction (EMI) in Korean higher education and how students experience this marginalisation. The general EMI setting in this study is Korean faculty teaching Korean undergraduate students and some international students in English. The Korean students in this study took EMI classes as a requirement for graduation at two elite private universities in Seoul, Korea. The findings from the analysis of qualitative data collected through individual interviews show that the adoption of EMI creates multiple layers of marginalisation. These layers include the marginalisation of students, languages (both Korean and English), and learning. On the basis of these findings, the article raises questions about the normalisation of marginalisation caused by EMI in higher education systems in non-English-speaking countries.