Background: A gap exists between patients' desire to be told about medical errors and present practice. Little is known about how physicians approach disclosure. The objective of the present study was to describe how physicians disclose errors to patients. Methods: Mailed survey of 2637 medical and surgical physicians in the United States (Missouri and Washington) and Canada (national sample). Participants received 1 of 4 scenarios depicting serious errors that varied by specialty (medical and surgical scenarios) and by how obvious the error would be to the patient if not disclosed (more apparent vs less apparent). Five questions measured what respondents would disclose using scripted statements. Results: Wide variation existed regarding what information respondents would disclose. Of the respondents, 56% chose statements that mentioned the adverse event but not the error, while 42% would explicitly state that an error occurred. Some physicians disclosed little information: 19% would not volunteer any information about the error's cause, and 63% would not provide specific information about preventing future errors. Disclosure was affected by the nature of the error and physician specialty. Of the respondents, 51% who received the more apparent errors explicitly mentioned the error, compared with 32% who received the less apparent errors (P<.001); 58% of medical specialists explicitly mentioned the error, compared with 19% of surgical specialists (P<.001). Respondents disclosed more information if they had positive disclosure attitudes, felt responsible for the error, had prior positive disclosure experiences, and were Canadian. Conclusions: Physicians vary widely in how they would disclose errors to patients. Disclosure standards and training are necessary to meet public expectations and promote professional responsibility following errors.