Pathogen transmission plays a major role in the development of healthcare-associated infections. The "patient zone" concept developed as part of the World Health Organization's "Five moments of hand hygiene" aims to distinguish surfaces primarily contaminated by flora of a single patient, i.e. the patient zone, from those the patient zone containing foreign and potentially harmful microorganisms. Discrepancies in healthcare provider (HCP) internal conceptual representations (i.e. mental models) of the patient zone may lead to missed infection prevention measures that could result in patient harm. We explored HCPs' mental models of the patient zone that shape how they interact with the work environment.We conducted individual concept mapping interviews supported by a card-sorting technique to examine HCPs' mental models of the patient zone and compared these to IPC expert models. Ten participants (five nurses, five physicians) without IPC specialization and two IPC experts provided definitions of the patient zone and allocated 32 items to "inside" or "outside" the patient zone while verbalizing their thought processes. We calculated similarity as percent agreement among participants and accuracy as percent allocated consistently with expert consensus. A content analysis of interview recordings served to identify mental models underlying the allocation decisions.Our study revealed limited similarity among participants, with seven of 32 items allocated consistently among all participants. Overall, 68% of items were sorted accurately according to expert consensus. Identified mental models were categorized as follows: "Patient contact", the patient zone defined according to objects having patient contact; "Sectors", the patient zone as a defined physical space; "Disinfection", the patient zone deduced based on need to disinfect hands and objects; and "Context-dependency", the patient zone defined depending on the context of an object's use.Our study revealed ambiguity surrounding the patient zone concept as evidenced by low similarity between participants and important discrepancies between participant and expert mental models. Such ambiguity may lead to inconsistent application of the patient zone concept and represents a patient safety risk. Initiatives to improve understanding and application of the patient zone concept should focus on establishing consistent, theoretically founded mental models.