In the age of technology development and internationalization, EMI (English as a Medium of Instruction) has been seen as a better method for resolving language problems of non-English students than teaching English in a single subject so as to meet the demand for employability in their future profession. However, EMI implementation is still a concern for educational researchers and instructors in many countries, especially in Asian Pacific regions. This research aimed to investigate EFL students' perspectives and challenges in learning an EMI program at a public technical university in Vietnam. To determine the obstacles of EMI learning from students' viewpoint, data were collected qualitatively by in-depth interviews with 18 EMI students in nine different academic disciplines randomly. The findings shed light on EMI implementation for tertiary education, as their perspectives on EMI courses' benefits are quite positive. However, this study also figured out several challenges due to students' poor ability in English interaction, vocabulary shortage, irrelevant course content, EMI lecturers' pedagogical methods, and students' motivations for the EMI course. This study provided some recommendations to help those interested in EMI in higher education enhance and develop EMI courses.