The adoption of English as a medium of instruction (EMI) in Thailand is not without difficulties. In this study, the needs and challenges of nursing students and teachers were explored qualitatively in a program where courses are allowed to be taught fully in English, fully in Thai or both in Thai and English. Focus group interviews for students were conducted, while semi-structured interviews were employed for teachers to gain in-depth knowledge about the topic at hand. Insights from students revealed the importance of English toward their career goals, their needs and challenges related to EMI (i.e., bilingual support system, clarification of technical terms, code-switching instruction), and their coping strategies when the lesson is challenging to comprehend. On the other hand, teachers confirmed the students’ language proficiency problems. In addition, they also reflected on their challenges in teaching the content subject in English, for example, the lack of time to prepare teaching materials in English. Teaching techniques were also elicited to respond to the learning challenges experienced by the students. Finally, practical implications were discussed to support students and teachers of EMI programs.