Evidence-based medicine is the judicious, conscientious, and explicit use of the best available evidence from clinical research in making clinical decisions. This definition recognizes a hierarchy of evidence that arranges study designs by their susceptibility to bias. The top of the hierarchy includes n-of-1 trials, systematic reviews of randomized trials, and single randomized trials reporting patient-important outcomes. The bottom of the hierarchy includes physiologic studies and unsystematic clinical observations. The definition posits that evidence alone is never enough to guide clinical decisions. In addition to evidence from clinical research, decision making requires careful and expert assessment of the patient's circumstances and elicitation of the patient's values and preferences. The latter should drive decisions, particularly when the trade-offs (of benefit and risk) are close or unclear. The evidence-based medicine process involves: (i) asking an answerable question; (ii) acquiring the best available evidence; (iii) appraising the evidence to judge the strength of inference of its results; and (iv) applying the results to the individual patient. Evidence-based endocrinology is hindered by limited high-level evidence assessing patient-important outcomes, limited systematic summaries of this evidence, lack of time, and lack of systematic training of endocrinologists in evidence-based medicine. Current endocrine practice may require a redesign to enhance the role of endocrinologists as information brokers for colleagues and patients. In the last 10 years, evidence-based medicine has matured as a philosophy of clinical care and medical education. An appraisal of its role in endocrinology awaits the pervasion of its principles into all of endocrine practice.