Research has indicated that questioning is used as an interactive way to engage students in learning English as a foreign or second language. In particular, rooted in Socratic philosophy, this strategy involves students in thinking and communicating ideas and knowledge to others for effective learning. However, teacher questioning in English classroom context in higher education in Viet Nam has not received much attention. Moreover, classroom questioning and teachers’ perceptions of this instructional practice facilitating students’ critical thinking in English major classes remained scarce. Therefore, this study aims to investigate the effects of questioning as pre-reading activity on students’ critical thinking in EFL reading classes. The participants in this study were 80 grade 12 students of the two classes at a high school, in Kien Giang province. Data collection in this study includes pre-tests, post-tests, questionnaires, and interviews. The findings from this study indicate that the implementation of questioning as a pre-reading activity by students in the experimental group yielded positive effects on students’ critical thinking in reading classes. Pedagogical implications for teachers and school administrators are made. Keywords: questioning, pre-reading activity, critical thinking, reading comprehension