The implementation of English as a medium of instruction (EMI) in primary education in Nepal is a growing phenomenon. Most schools in Nepal incorporate EMI in their education delivery process. In the process of adopting EMI, they have faced numerous challenges. This paper takes a qualitative design and narrative approach to explore the challenges faced by teachers in implementing EMI in primary education. Narrative inquiry was conducted with four head teachers of different schools, which were selected purposively. Findings and discussion indicated that lack of expert teachers, lack of appropriate teaching materials, learners' linguistic background, limited exposure to the English language, and contradiction between policy and practice are the major challenges to implementing EMI in primary education. Despite such challenges, teachers, students, institutions, stakeholders, and policymakers saw EMI as a worthwhile opportunity.