Objectives: Little is known about how patients perceive diagnostic uncertainty. We sought to understand how patients and care partners perceive uncertainty in an emergency or urgent care setting, where making a final diagnosis is often not possible., Methods: We administered a survey to a nationally representative panel on patient-reported diagnostic excellence in an emergency department or urgent care setting. The survey included items specific to perceived diagnostic excellence, visit characteristics, and demographics. We analyzed responses to two open-ended questions among those who reported uncertainty in the explanation they were given. Themes were identified using an inductive approach, and compared by whether respondents agreed or disagreed the explanation they were given was true., Results: Of the 1,116 respondents, 106 (10 %) reported that the care team was not certain in the explanation of their health problem. Five themes were identified in the open-ended responses: poor communication (73 %), uncertainty made transparent (10 %), incorrect information provided (9 %), inadequate testing equipment (4 %), and unable to determine (4 %). Of the respondents who reported uncertainty, 21 % (n=22/106) reported the explanation of their problem given was not true., Conclusions: The findings of this analysis suggest that the majority of patients and their care partners do not equate uncertainty with a wrong explanation of their health problem, and that poor communication was the most commonly cited reason for perceived uncertainty., (© 2023 Walter de Gruyter GmbH, Berlin/Boston.)