Evidence-based medicine (EBM) is a concept that has grown to dominate the medical literature over the last decade. EBM has provoked a variety of criticisms, scientific, philosophical and sociological. However, while its basic conclusion--that we should practise EBM--is ethical, there has been limited ethical analysis of EBM. This paper aims to provide an analysis of EBM from an ethical perspective and identify some of EBM's potential ethical implications. Following a description of what constitutes EBM, this paper will identify and assess some of the basic values and epistemological assumptions of EBM that provide support for the moral duty to practise EBM. It will then examine potential ethical implications that could arise from practising EBM, given the challenges that have been made of EBM's assumptions and claims to authority. This paper will conclude by arguing that practitioners could strengthen the ethics of EBM by embracing a broader definition of evidence and including ethical criteria in the critical appraisal of research studies.