Research studies have shown the benefits of employing written peer feedback (WPF) in classrooms around the world. However, implementing it appropriately in the classrooms is not consistent in the context of universities in Vietnam. The current paper explored the extent to which WPF had applied in the academic writing English classrooms at a university in Vietnam and the practical perceptions of the lecturers and students on this issue. 338 out of 996 students and three lecturers were participated to respond to the survey questionnaire and interviews for analysis. The study revealed that though WPF was carried out in most academic writing classrooms, the implementation was not sufficient to take full benefits of this kind of activity. The students were not sufficiently trained to use this activity appropriately. However, the students obtained highly positive perceptions towards the use of WPF in the classrooms because it provided students opportunities to learn from each other and improve their writing outcomes