In this study, we aim to investigate the types of questions that Taiwanese mathematics teachers pose and in which instructional situations they do so during mathematics lessons at the secondary school level. The classroom teaching of six experienced mathematics teachers was analyzed. Quantitative analysis showed that the mathematics teachers tend to give lectures rather than ask questions. When the mathematics teachers posed questions, only about one-fifth of the questions require students to provide high-cognitive responses. We also observed that the mathematics teachers differed in the number and type of questions they asked in different instructional situations. A cross-examination of the types of questions and the lesson structures revealed that two-thirds of the mathematics teachers asked high-cognitive questions when practicing or reviewing the content with the students. The qualitative analysis further identified three instructional purposes for high-cognitive questions: connecting the meaning of mathematical concepts, stimulating multiple solutions to a problem, and exploring mathematical relationships across different problem contexts. The results imply that mathematics teaching at the secondary school level in Taiwan is more teacher-centered, and the mathematics teachers do not often ask questions during classroom teaching. However, the teachers tend to ask high-cognitive questions for assessment purposes to ensure that the students have understood the concepts and can proceed to advanced mathematics.