The relationship between board certification (and recertification) and patient outcomes is coming under increasing scrutiny as a means to improve the quality of medical care. Since > 5 years remain before individuals certified in sleep medicine under the American Board of Medical Specialties will be required to recertify (and board certification by the old American Board of Sleep Medicine is lifelong), evidence related to initial board certification is most relevant and, moreover, only that which relates to cognitive skills rather than procedural abilities. In the most recent systematic review available, Sharp et al2 examined published studies through 1999 and concluded that, overall, there was an association between board certification and more positive clinical outcomes: 16 studies demonstrated better clinical outcomes for board-certified physicians, 14 showed no association, and three studies found that such physicians had worse outcomes. Two other studies were of such low quality that no conclusions were justified. An increasing number of studies examining board certification and outcomes in a variety of practice areas have been published since then, including three studies of outcomes for patients with acute myocardial infarction (AMI). Two reports used data collected by the Pennsylvania Health Care Cost Containment Council: One found a 15% reduction in mortality when care was rendered by a board-certified cardiologist, internist, or family medicine physician compared with physicians who designated themselves as practicing these specialties but who were not certified3; the second revealed a 19% decrease in AMI mortality for patients treated by board-certified internists or cardiologists compared with internists or cardiologists who sat for, but failed, their certification examinations.4 A third study analyzed the Medicare Cooperative Cardiovascular Project database of 101,254 patients hospitalized for AMI.5 These investigators found that board-certified family practitioners, internists, and cardiologists exhibited greater use of aspirin and β-blockers, as recommended by clinical practice guidelines, than their noncertified colleagues. The quality of anesthesia care was studied in 144,883 patients undergoing orthopedic or general surgical procedures using Medicare claims records encompassing the period 1991 to 1994.6 When 8,894 cases performed by mid-career, non-board-certified anesthesiologists were compared with the remaining cases that were carried out by board-certified clinicians, adjusted ORs for 30-day mortality and failure to rescue were significantly higher for anesthesiologists who were not certified. Finally, Reid et al7 reported on a study of 10,408 Massachusetts physicians from claims submitted to commercial insurers on 1,704,686 episodes of care, assessing quality of care using the RAND Quality Assessment Tools rating key processes of care. Of the three physician characteristics that predicted better overall quality of patient care, board certification was associated with the most significant effect.