Investigating the dynamics of English for Medical Purposes (EMP) textbook design and use in China

English for Medical Purposes (EMP) education is extensively implemented at universities in China. EMP textbooks are crucial for providing medical students with access to authentic medical language and supporting general English teachers' transition to EMP instruction. The limited existing research on EMP textbooks in China has largely relied on researchers' impressions or teachers' evaluations rather than analyzing textbook content. Broader ESP literature has given limited attention to textbook designers' selection of text types, adaptations of authentic materials, and design of authentic tasks, and has rarely connected textbook design to textbook use. This research analyzed a commonly used EMP textbook in China, focusing on text type, text authenticity, and task design, and used questionnaires to explore how EMP teachers and learners used their textbooks. It aimed to reveal relationships between EMP textbook design and use and provide insights into effective EMP textbook design and ways to maximize its impact. The textbook analysis showed that the textbook writers adapted authentic texts and offered limited text type variety and tasks with restricted authenticity. Questionnaire findings showed that the teachers actively adapted their EMP textbooks through addition, deletion, and modification, and that the learners exercised autonomy in their textbook use through selective content focus and personalized learning methods. These findings provide empirical evidence that EMP textbook design may influence how teachers and learners use textbooks, while highlighting their autonomy in maximizing the textbook's impact. This research offers recommendations for improving EMP textbook design and enhancing effective textbook use by teachers and learners.