OBJECTIVES: To find out whether and how the teaching of medical ethics can influence attitudes on accepting treatment refusals. SETTING AND DESIGN: Anonymous questionnaires were distributed to 4 groups of students at the University of Geneva who had participated (P) or not (nP) in teaching modules on medical law and ethics. One vignette described a terminally ill patient refusing mechanical ventilation, another a Jehovah's Witness refusing a life-saving blood transfusion. PARTICIPANTS: 127 medical and 168 law students. MAIN OUTCOME MEASURES: 5-point Likert scale of responses to the vignettes reaching from certain acceptance to certain non-acceptance of the treatment refusal. RESULTS: More than 80% of law students (nP) said that a good physician should accept the terminally ill patient's refusal. 84% (P) compared to 68% (nP) of medical students (P=0.03) would accept this refusal. The acceptance of the Jehovah's Witness refusal of a life-saving transfusion was less among all students. Students from the groups (P) reported significantly more often (P < 0.001) that they would accept (76% of medical students) or that a good physician should accept (63% of law students) the treatment refusal of the Jehovah's Witness than medical students (48%) and law students (27%) from the two other groups (nP). CONCLUSION: (P) students showed significantly more acceptance of treatment refusals in the hypothetical case scenarios than (nP) students from the same faculty. Religion, cultural origin and school education of the parents had less influence on attitudes than participation in ethical teaching and type of student (medicine vs. law).