Student ratings of instruction can be a valuable indicator of teaching because the quality measurement of instruction identifies areas where improvement is needed. Student ratings of instruction are expected to evaluate and enhance the teaching strategies. Evaluation of teaching effectiveness has been officially implemented in Taiwanese higher education since 2005. Therefore, this research investigated Taiwanese EFL university instructors' perceptions toward student ratings of instruction and the impact of student ratings of instruction on EFL instructors' classroom teaching. The data of this quantitative study was collected by 21 questionnaires. 32 qualified participants were selected from ten universities in the northern part of Taiwan. The results indicate those EFL instructors' perceptions and experiences toward student ratings of instruction affects their approach to teaching, but EFL instructors do not prepare lessons based on the results of student ratings of instruction.