This study investigated how teachers perceived the benefits and difficulties of implementing a Lesson Study (LS) in the context of English language teaching at a university in Vietnam. The data were collected from six teachers through semi-structured interviews. To analyze the data, two addressing themes (teachers’ perceived benefits and teachers’ perceived difficulties) were focused on while implementing LS. The results generally showed that the teachers believed that LS brought them three benefits: encouraging teachers’ exchange activities and helping them deepen knowledge of lesson content, understanding students’ learning activities and working processes, and promoting teachers’ motivation in pursuing their continuous professional development (CPD). Regarding teachers’ perceived difficulties in LS implementation, they reported lacking confidence in actively implementing LS activities. Additionally, they had difficulties in time management and encountered problems reaching a consensus for joint work due to the influence of muti-faceted aspects. Accordingly, the study provides pedagogical implications for related stakeholders (teachers, students, and policymakers) regarding LS implementation issues contributing to the success of LS implementation in Vietnam and other similar contexts.