Purpose: The objective of the present study is to analyze the effects of the transition to English Medium Instruction (EMI) on lecturers in Spanish universities in one specific area, namely Operations Management courses taught in Business degrees. Methodology: After reviewing the bibliography, we designed a questionnaire based on previous research into EMI in non-Anglophone countries. By administering this online, we gathered information from 20 EMI lecturers giving Operations Management courses in thirteen Spanish Universities. The data were analyzed by means of a descriptive analysis of the closed-ended questions and thematic content analysis of the open-ended questions. Findings: Most professors report that they initially reacted negatively to the idea of having to teach in English, but now realize that most of their fears were ungrounded. They emphasize that it is very important to invest time in training seminars and the exchange of experiences. Other relevant findings are the perceived lack of incentives to teach in English, the need to use tools and techniques to improve the interaction with students, and the considerable amount of time needed for class preparation. Our results are discussed in the light of the bibliography on EAU and recommendations are made with regard to the implementation of EMI in Operations Management courses and related areas. Originality/value: The results of this small-scale study of EMI in OM shed important light on how EMI is impacting on one field. They are consistent with previous research elsewhere, but also provide some insights that may pave the way for further research and development.