Modern medical ethics has effected dramatic changes in medicine. Yet teaching medical ethics still presents many challenges. The main teaching methods used--inpatient ethics consultations, courses, and case conferences--have notable weaknesses. In addition, the attitudes and knowledge gaps of some learners may hamper these methods further. To encourage open discussion of the challenges, we outline our current approach to teaching medical ethics. We teach with the conviction that ethics instruction gives physicians vital knowledge not available from science. Our teaching addresses ethical issues directly relevant to residents and students, emphasizes a few important concepts, and nurtures learners' critical reasoning skills. Our teaching also tries to use scarce faculty time efficiently. However, we believe successful medical ethics teaching requires medical schools to commit significant material and moral support. We hope the discussion here encourages medical ethics teachers everywhere to describe the challenges they face and to collaborate on finding solutions.