Although blended learning (BL) has emerged as one of the most dominant delivery modes in higher education in the 21st century, there are notable barriers and drawbacks in using BL for English language teaching and learning in Vietnamese universities. This study reports on research into the use of BL, conducted through semi-structured interviews with 30 English as a Foreign Language (EFL) lecturers from 10 different universities across the two major cities of Vietnam. The findings revealed that EFL lecturers identified eight groups of barriers and four groups of drawbacks to the successful implementation of BL. The most significant barriers included: lack of infrastructure and technology, institutional policies and support; lack of knowledge, experience and investment in using BL; lack of technological competence and information technology (IT) skills and lack of teaching time to employ web-based technologies and online resources in classrooms. Meanwhile, the most crucial drawbacks were: lecturers’ workload, ineffective use of BL, time consumption and demotivation. The authors point to the underlying factors contributing to these barriers and drawbacks and make implications for how some of these can be effectively addressed through constructive changes to policy and practice.