Introduction: The value of using patient- and physician-identified quality assurance (QA) issues in emergency medicine remains poorly characterized as a marker for emergency department (ED) QA. The objective of this study was to determine whether evaluation of patient and physician concerns is useful for identifying medical errors resulting in either an adverse event or a near-miss event. Methods: We conducted a retrospective, observational cohort study of consecutive patients presenting between January 2008 and December 2014 to an urban, tertiary care academic medical center ED with an electronic error reporting system that allows physicians to identify QA issues for review. In our system, both patient and physician concerns are reviewed by physician evaluators not involved with the patients’ care to determine if a QA issue exists. If a potential QA issue is present, it is referred to a 20-member QA committee of emergency physicians and nurses who make a final determination as to whether or not an error or adverse event occurred. Results: We identified 570 concerns within a database of 383,419 ED presentations, of which 33 were patient-generated and 537 were physician-generated. Out of the 570 reports, a preventable adverse event was detected in 3.0% of cases (95% CI = [1.52–4.28]). Further analysis revealed that 9.1% (95% CI = [2–24]) of patient complaints correlated to preventable errors leading to an adverse event. In contrast, 2.6% (95% CI = [2–4]) of QA concerns reported by a physician alone were found to be due to preventable medical errors leading to an adverse event (p=0.069). Near-miss events (errors without adverse outcome) trended towards more accurate reporting by physicians, with medical error found in 12.1% of reported cases (95% CI = [10–15]) versus 9.1% of those reported by patients (95% CI = [2–24] p=0.079). Adverse events in general that were not deemed to be due to preventable medical error were found in 12.1% of patient complaints (95% CI = [3–28]) and in 5.8% of physician QA concerns (95% CI = [4–8]). Conclusion: Screening and systemized evaluation of ED patient and physician complaints may be an underutilized QA tool. Patient complaints demonstrated a trend to identify medical errors that result in preventable adverse events, while physician QA concerns may be more likely to uncover a near miss