Although many researchers have studied the perspectives on adoption of English as a curricular innovation and compatibility of English as a medium of instruction which mostly take place among language planners, policy makers, educators and researchers, few have examined how the students perceive English-medium instruction and how students' perceptions of English-medium instruction may affect the content learning and learning motivation. The English-medium curricula design has generally failed to use the perceptions and experiences of students. This review of studies addresses about the English as a medium of instruction from students' points of view and explores reasons behind students' perceptions concerning the language of instruction. To this review, language planners, policy makers, educators and researchers will better understand the pros and cons of Thai and English as medium of instruction in Thai universities as well as the relevant factors which influence the perception of medium of instruction. In future, therefore, they can base their decisions of language choice between Thai versus English as a medium of instruction on clear knowledge of popular preferences.