Ethical and professional guidelines,1- 3 credentialing organizations,4 patient safety organizations,5 and experts on medical errors advocate disclosure of medical errors to patients and families,6- 19 but there is little empirical evidence to guide practitioners. We found empirical support for concluding that disclosure often does not occur,22,28,30,32,36 that patients and the public favor disclosure,23,24,29,32,34 and that physicians support disclosure,23,28,32 but we found no empirical results to guide practitioners with respect to the practical questions of who, what, when, and how to disclose. Because best process is defined by best outcomes, answers to these questions await an understanding of the relationship between the process and consequences of disclosure. Insufficient empirical data exist to evaluate whether full disclosure results in benefits for patients, providers, and organizations or whether expectations of negative consequences are unfounded. Medical malpractice litigation provides an example of a potential negative consequence. Fear of litigation has been cited as a significant obstacle to disclosure.31 In focus group discussions, physicians noted that fear of litigation might limit their statements to patients and inhibit the offer of an apology.23 Fear of malpractice litigation was reported by risk managers to be a barrier to disclosure more frequently than any other barrier studied.35 The findings of Witman and colleagues29 have often been cited to support the assertion that disclosure may reduce litigation risk. However, this assumes a link between patients' responses to hypothetical scenarios and their responses to actual errors, and such a link has not yet been established. The results of the implementation of the extreme honesty policy at the Lexington VA facility25 are encouraging, but the unique characteristics of the VA system, the patients served, and the legal status of providers within that system make it questionable whether similar results would be obtained in other settings. Studies27,31,33,38 of patients and families considering or involved in litigation suggest the importance of explanation and apology, but findings from such studies are suggestive rather than conclusive, and correlation and causation are not yet established. Other research findings suggest that the characteristics of the injury, the physician-patient relationship before the adverse event, the physicians' communication skills, and the patients' financial status are influential in litigation decisions.39- 43 Evaluation of the relative importance of each of these factors and the specific components of disclosure should be a goal for future research. Fear of malpractice litigation is not the only barrier to disclosure; physicians may also anticipate patient distress, patient attrition, damage to their reputation, license revocation, loss of privileges, and other consequences.6- 8,11,16,19,22,44 Future research should seek to determine the extent to which such concerns are in fact barriers and then evaluate methods for minimizing the likelihood of anticipated negative consequences.