This research aims to investigate the teachers’ guideline in designing Multiple Choice Questions (MCQs) and explore the teachers’ challenges in following their guideline in designing MCQs for the English assessment in one private high-school in Yogyakarta. To collect the data, the researcher used qualitative research design and interview as the data collection method. The participants of this research were two English teachers in one private high-school in Yogyakarta. The study found that there were fourteen guidelines used in designing MCQs by teachers in one private high-school in Yogyakarta. The guidelines; were teachers used the correct grammar; teachers used the materials in accordance with the indicator; the option materials used must be homogeneous and logical, teachers used only the necessary statement; teachers did not make questions that gave clues to the correct answer; teachers used a clear and functional chart, table, picture, graph, or diagram; teachers did not made a question depended on the answer of previous question; teachers used book of scoring technique; every question must have only one correct answer; teachers designed question clearly; the teachers did not place the correct answer in the same position; teachers designed the option sentence same in the length; and teachers used communicative language. In addition, there were five challenges faced by the teachers in applying their guidelines. The challenges were designing a good MCQs took a long time, making an effective and a functional distractor, making a lot of number of MCQs, having no guidance of senior teacher in applying the guidelines, and making question that did not provide the clue to the correct answer to the students.