Engineering schools have spearheaded the implementation of English-medium instruction (EMI) in Korean higher education. Three major engineering universities were chosen for this study with its goals to examine engineering students' perceptions of EMI and L1 use in EMI classes and to make suggestions for the directions that Korean engineering schools should take in relation to EMI. A questionnaire survey was conducted among the undergraduate students of the three universities. Five hundred twenty-four students participated in the survey, and the results show that more students felt insufficient about their English ability than sufficient and that the majority of the students preferred Korean-medium instruction over EMI and did not find EMI beneficial for their English ability. Nevertheless, most of the survey participants believed that EMI should be maintained but with changes in the schools' mandatory policies. In addition, the students without distinction as to school were supportive of L1 use in EMI classes: approximately 90% of the respondents from each school believed that L1 should be used to facilitate their learning.