Critical thinking has been claimed to have an important impact on learners’ reading comprehension because it can help them analyze, evaluate, construct their thinking, solving problems and reasoning (Ennis, 1989). The current case study aims mainly to investigate in depth the teacher’s questions and students’ critical thinking in high school EFL reading classrooms in the Mekong Delta context. The first purpose was to explore the common features including frequencies of teacher’s questions and the second one was to ascertain whether the teacher’s questions could facilitate students’ critical thinking. Classroom observations and the cognitive domain of Bloom’s taxonomy were adapted as the instruments of the present research. The study results reveal common types of questions that high school teachers often use in reading lessons in a high school for the gifted in the Mekong Delta. Suggestions are made on types of questions that teachers should use more in their class in order to enhance students’ critical thinking.