Objective: To assess the impact on ordering errors when physicians stopped handwriting patient identifiers on requests for blood transfusion. Material and Methods: Physicians, frustrated by the amount of time required to complete paper forms to order blood, asked if the requirement for handwritten patient identifiers, which were in addition to such information "stamped" on blood requests, could be eliminated. We acquiesced to the request, modified the blood ordering forms accordingly, and continued to monitor ordering errors. Results: After elimination of the handwritten identifiers in 1997, ordering errors increased from an annual rate of 1 in 10,000 to 6 in 10,000 blood requests by late 1999. We alerted the clinicians by newsletter, and the rate decreased somewhat (3 in 10,000 requests). However, the error rate did not decrease to its previous level of 1 in 10,000 requests until mid-2001, about 2 1/2 years after reinstitution of the requirement for handwritten patient identifiers. Conclusion: An obligatory second entry of demographic identifiers on a blood order requires ordering physicians to carefully consider the identity of the patient receiving a transfusion and reduces the likelihood of transfusion of. an unintended recipient. Error management tools, such as a predetermined method for planning, reviewing, and documenting all changes, facilitate detection of trends and responses to corrective actions.