ABSTRACT
Summary Evidence-based medicine (EBM) has been described by Sackett et al. as ?the integration of best research evidence with clinical expertise and patient values?. This chapter discusses core elements of EBM with particular reference to clinical research in transfusion medicine, and provides a practical approach to searching for evidence and critical appraisal, with some considerations of different study designs. It also includes a review of how the evidence base for transfusion medicine was collated in response to the COVID-19 pandemic. One important component of EBM is the critical appraisal of the evidence generated from a study. One important aspect of clinical trial appraisal concerns the understanding of chance variation and sample-size calculation. Appraising the evidence base for transfusion medicine is one part of improving practice;another is the effective dissemination of the evidence to clinicians.