By making the clinical decision making process explicit, conscious, and science based, we may avoid confusing opinion with evidence. EBM may help sharpen our critical appraisal skills and thus improve the way we practice, teach, and conduct research. Nevertheless, EBM will need to supplement rather than substitute for other approaches to patient care and teaching. EBM may better incorporate patients' values into clinical decision making, and this may be especially important in anesthesiology, where we are in need of valid evidence about important clinical issues such as preoperative testing and postoperative analgesia. By incorporating valid scientific evidence and patients' values into clinical decision making, we may improve patient outcomes. Outside of internal medicine, the literature suggesting that the practice of EBM improves outcomes is sparse, though increasing. Future studies to critically evaluate the practice of EBM in anesthesiology and critical care would be helpful.