Patient identification is an essential step in hospital risk management and a key factor in transfusion safety. When taking a blood sample, the probability of mistaking a person’s identity is estimated at around 1/2,000. This can lead to diagnostic errors and/or inappropriate therapeutic patient management. In addition, the impact in terms of transfusion safety is major because mistaken identity can lead to ABO incompatibility, which can be fatal, as will be explained below. The causes of identitovigilance errors are diverse, but human factors are predominant. As part of the risk management process, various measures can be implemented to reduce the risk of WBIT (Wrong Blood in Tube): determining a patient’s blood group using two samples taken at different times plays a very important role. Staff training, adherence to procedures, and incident analysis are also essential and valuable tools. Finally, patient involvement in the safety of their care must become a “standard of care”.