Clinical ethical reasoning and analysis are skills as central to good patient care as the efficient application of biomedical knowledge to diagnosis and prognosis. However, experience in teaching clinical ethics to senior medical students has indicated that simply trying to 'apply' the knowledge learnt about ethical theories, principles, concepts and rules in the clinical setting does not ensure ethical competence in clinical decision-making. In 1992, we developed and piloted a three-session programme that focused on a more systematic approach to the way students identified and attempted to manage ethical issues in their clinical practice. This programme was modified and improved in 1993 and further expanded in 1994. Our experience suggests that many students are now better able to bridge what has been called the 'gap' between the possession of ethical knowledge and its actual use in clinical decision-making. The remaining problem was assessment. How do you assess clinical ethical reasoning and decision-making? In the preclinical years of medical education, knowledge-based assessment tools, like the modified essay question (MEQ), provide a means for assessing the sensitivity of students to ethical issues. However, such tools permit neither an appraisal of how students actually make clinical ethical decisions, nor which factors students perceive as important in making an actual clinical decision. In order to make this type of appraisal, we developed a format for a written case report that facilitated our assessing the process as well as the end-product, the decision.(ABSTRACT TRUNCATED AT 250 WORDS)