This Technical Report addresses the issue of multiple identifiers that may refer to the same person. It describes the management of patient identification and cross-referencing of identities and provides some practical guidance for addressing implementation of standards, reports, guidelines, methods, etc. The need to identify a person unambiguously is an important component for the interoperability of health information systems.Within healthcare there is an essential requirement for good quality information, not least to uniquely identify an individual to ensure that the appropriate and relevant care can be delivered irrespective of geography, time and situation. To ensure that health care providers have access to information about an individual patient, it is vital that the patient can be reliably identified within a Health Care Information System. Currently, a given patient may have several identifiers corresponding to different geographical locations, different health care organisations or various specialities. The allocation of multiple identifiers and related processes increases the risk of identification error within one or more information systems and as a result, might compromise the safety of a patient.The quality of identification ensures that health care providers have access to patient information, facilitating closer coordination and continuity of care, improving service in terms of prevention and follow-up. Quality will be pursued within the framework of:—medical care in a hospital information system (HIS): covering all the stages from patient identification to admittance to the health care organization or directly to the care unit or emergency care, through to the issuing of reports by the different health care services (medical and medico-technical services);—continuity of care;—patient mobility.Because electronic heath care records may be updated by several and various healthcare providers over a long period of time, the patient identification needs to be formalized in such a way to ensure that the correct patient’s healthcare record is being accessed.In the regions or the countries where a national unique patient identifier is not used, the patient is identified by using patient identifiers for each healthcare system, wherever the patient is registered. Even within an individual healthcare organization, the patient may be identified by a specific identifier for an individual ward or a medical support unit. To ensure the continuity of care and the sharing of patient information, it is necessary to reliably link together the different patient identities within what we will call a "patient identifier cross-reference domain".The need to cross-reference identities appears when a healthcare provider wants to access all the healthcare information for one patient and that information is contained in different healthcare systems managed by several healthcare professionals or organisations.In recent years, many research studies and implementations have taken place to try to resolve this issue. This document provides an overview and proposals for the management of the patient identities and the cross referencing of identities and provides guidance for authorities, organisations, project managers and users.