This study aims to understand international students' learning experiences in English as a medium of instruction (EMI) courses in a private Korean university. By using mixed-method research, this study collected two data sources, including (1) an online survey (n=46) and (2) an individual in-depth interview (n=4) at the end of the 2022 Spring semester. The study results are summarized as follows. First, EMI courses could enhance international students' content knowledge development effectively. Second, EMI courses could improve international students' English proficiency in terms of reading and vocabulary ability. Third, international students showed high satisfaction with EMI courses and are willing to take EMI courses continuously. However, the interview analysis showed that it was challenging for a few international students to improve their English speaking ability due to limited opportunities to speak English during graduate-level courses. These study results suggest several recommendations to provide practical EMI courses for teaching diverse international students, including English language learners in higher education.