Abstract: English is the most widely used language in the world, which has a great influence on students’ future job opportunities. That is the reason why this subject has been put into the curriculum of Vietnamese students at an early age with the purpose of helping them master this language. There are many factors that affect students’ ability and teaching method is one of the most important factors. Although warm-up activities are not the key things in the teaching and learning method, it has contributed to creating an effective learning environment and inspiring them to learn. In this way, students can feel more relaxed before learning. This research aims at investigating the perception and practice of warm-up activities by English teachers in Thai Nguyen. A sample of 6 teachers and 197 students from three different secondary schools in Thai Nguyen city participated in this study. There were several data collection instruments used, including teachers’ interviews, observation, and students’ questionnaires. The results of this research showed that all teachers have a positive opinion towards using warm-up activities in their classes. They also have some similarities and principles in implementation. Hopefully, this study will make a small contribution to clarify the perception as well as the practice of teachers in using warm-up activities in English classes.