In this paper we set out to examine the arguments for and against the claim that Evidence-Based Medicine (EBM) will improve the quality of care. In particular, we examine the following issues: 1. Are there hidden ethical assumptions in the methodology of EBM? 2. Is there a tension between the duty of care and EBM? 3. How can patient preferences be incorporated into quality guidelines and effectiveness studies? 4. Is there a tension between the quality of a particular intervention and overall quality of care? 5. Are certain branches of medicine and patient groups innately or prima facie disadvantaged by a shift to EBM? In addition we consider a case study in the ethics of EBM, on a clinical trial concerning the collection of umbilical cord blood in utero and ex utero, during or after labour in childbirth.