Background/purpose. This study presents the development of a novel questionnaire to assess medical students' motivation to learn English for Medical Purposes (EMP), addressing a gap in existing tools tailored to specific language contexts. Based on Dörnyei's L2 Motivational Self System, the questionnaire uniquely contextualizes its items to address the specific circumstances of medical students. Materials/methods. Data were collected from 283 medical students (undergraduate, years 1 to 6) studying in programs with Hungarian as a medium of instruction at the four medical schools of Hungary. The reliability of the variables for each dimension was verified by Cronbach's [alpha] and McDonald's [omega]. The Kaiser-Meyer-Olkin measure of sampling adequacy and Bartlett's test of sphericity confirmed the data's suitability for principal component analysis (PCA), which was conducted to establish the structure of variables for each dimension. Results. The PCAs demonstrated that the adapted questionnaire has a clear and interpretable component structure. The findings reveal that the respondent medical students are largely intrinsically motivated, driven by constructs such as the Ideal L2 Self and Self-Efficacy. Conclusion. This research contributes an empirically tested, adaptable instrument for measuring EMP motivation across diverse national contexts and underscores its potential to inform targeted curricular innovations that enhance engagement through authentic, goal-oriented educational practices.