Given that Vietnamese high school students continue to be passive knowledge receivers in their learning of writing although learner autonomy can make these students more active and independent writers, this qualitative study was conducted to explore six EFL teachers' beliefs about the necessity and viability of developing learner autonomy in writing classrooms at one public high school in Vietnam. Results from seven interview questions showed that all the teachers recognised the necessity of building up learner autonomy in EFL writing learning, and appreciated the potential contribution of learner autonomy to writing skills development. However, only half of the teachers saw positively the viability of promoting writing autonomy, while the other half was sceptical about its feasibility. The teachers elucidated the advantages and barriers in fostering learner autonomy in EFL writing learning pertaining to teachers' roles, learners' responsibilities, and school environment. Based upon the findings, recommendations are made for teachers to promote learner autonomy in writing skills development.