Practice guidelines are rapidly becoming preferred decision-making resources in medicine, as advances in technology and pharmaceutics continue to expand. An evidence-based approach to the development of practice guidelines serves to anchor healthcare policy to scientific documentation, and in conjunction with practitioner opinion can provide a powerful and practical clinical tool. Three sources of information are essential to an evidence-based approach: a) an exhaustive literature synthesis; b) meta-analysis; and c) consensus opinion. The systematic merging of evidence from these sources offers healthcare providers a scientifically supportable document that is flexible enough to deal with clinically complex problems. Evidence-based practice guidelines, in conjunction with practice standards and practice advisories, are invaluable resources for clinical decision making. The judicious use of these documents by practitioners will serve to improve the efficiency and safety of health care well.