Context: Despite the best efforts of health care practitioners, medical errors are inevitable. Disclosure of errors to patients is desired by patients and recommended by ethicists and professional organizations, but little is known about how patients and physicians think medical errors should be discussed. Objective: To determine patients' and physicians' attitudes about error disclosure. Design, Setting, and Participants: Thirteen focus groups were organized, including 6 groups of adult patients, 4 groups of academic and community physicians, and 3 groups of both physicians and patients. A total of 52 patients and 46 physicians participated. Main Outcome Measures: Qualitative analysis of focus group transcripts to determine the attitudes of patients and physicians about medical error disclosure; whether physicians disclose the information patients desire; and patients' and physicians' emotional needs when an error occurs and whether these needs are met. Results: Both patients and physicians had unmet needs following errors. Patients wanted disclosure of all harmful errors and sought information about what happened, why the error happened, how the error's consequences will be mitigated, and how recurrences will be prevented. Physicians agreed that harmful errors should be disclosed but "choose their words carefully" when telling patients about errors. Although physicians disclosed the adverse event, they often avoided stating that an error occurred, why the error happened, or how recurrences would be prevented. Patients also desired emotional support from physicians following errors, including an apology. However, physicians worried that an apology might create legal liability. Physicians were also upset when errors happen but were unsure where to seek emotional support. Conclusions: Physicians may not be providing the information or emotional support that patients seek following harmful medical errors. Physicians should strive to meet patients' desires for an apology and for information on the nature, cause, and prevention of errors. Institutions should also address the emotional needs of practitioners who are involved in medical errors.