"Auto-anti-A1" has been sparsely discussed in the literature. Only few workers in the past depicted such antibody in transfused and nontransfused patients. The current case is probably the first example of auto-anti-A1 in a healthy young blood donor who was typed as ABO Group "A1B." The cold reacting autoantibody in the donor was serologically characterized in details and was found to be nonhemolytic. ABO discrepancy was resolved and the donor was finally typed as "A1B Negative." Therefore, we concluded that auto-anti-A1 may be a rare cause of ABO discrepancy and its resolution is essential to confirm blood group and subsequent blood transfusion management.