Introduction: In recent decades, health care policy makers and even general population have seriously paid attention to disclosure of medical errors (DME). However, the authors of this study didn’t find any study of this field in Iran. The aim of this study was the assessment of physicians and residents attitude about DME.Methods: In this cross-sectional study, 107 physicians and residents of surgical and internal specialty of Imam Khomeini hospital in Tehran were randomly selected. Goals of study were explained to participants. Then, any participants filled a questionnaires containing of demographic data (age, sex and specialty) and medical errors (amount of any types of medical error per year that occurred by them) and questions about their attitude of medical errors disclosure.Findings: Median (quartile 25% -75%) of major, minor and near miss medical errors occurred per year were 0 (0-1), 2 (0-4) and 1.5 (0-3), respectively. Disclosure of major, minor and near miss medical errors have been approved by (77%), (53%) and (44%) of participants, respectively. 83% of participants displayed that disclosure of medical errors to patient, by her/his doctor, is very difficult. “Patients litigation due to DME by her/his doctor” (50%) was The most common cause of difficulty of DME. Ninety percent of participants knew medical error disclosure as one of the main challenges of health care system and revealed that creation of a comprehensive system to promote DME is essential. Major medical errors have been occurred by females were significantly higher than males (0.94 vs. 0.79, P=0.043) and by residents were significantly higher than physicians (1.06 vs. 0.63, P=0.019).Conclusion: The findings of this study showed that although the majority of participants approved DME, ninety percent of them still knew DME as one of the main challenges of health care system and revealed that creation of a comprehensive system promote DME is essential. These results indicate that nowadays DME process requires serious attention of policymakers in health care system, in Iran.