Currently, patient misidentification in healthcare organizations is a risk that can lead to diagnostic errors, performing of surgical procedures, and administration of medicines or hemoderivates to wrong patients. The organizations that deal with patient safety promote methods that guarantee unique identifications within the strategies for improving safety in healthcare. Identification policies are obligatory to ensure the accuracy of the identification in all patients using universally implemented unique methods, and healthcare workers have the responsibility of verifying patient identification with appropriate documents when a diagnostic or therapeutic procedure is planned. In this paper we review the bases for an unmistakable unique identification and present the experiences of five regional health services that develop the policies promoted in Spain by the Quality Agency of the Ministry of Health and Consumer Affairs.