The objective of this paper is firstly to find how the students in Korea respond to teachers` and students` L1 use in the classroom. Secondly, it investigates the most effective use of the L1 in relation to the students` needs and their English acquisition. The study is based on a survey of a group of students (319 students) studying at D-university in Korea. The data was analysed statistically using SPSS software. The analysis of the data reveals that the switching to L1 is common in the English only class of D-university Furthermore, the limited and judicious use of the first language in the EFL class does not seem to hinder the students` ability to learn English but rather could be helpful for the teaching and learning processes.