This project, currently supported by Lantana Consulting Group, HaploGNX, and San Diego Blood Bank, will create a FHIR Implementation Guide to exchange extended RBC phenotyping and genotyping information. Lantana is socializing this effort to bring it to the attention of additional interested parties such as software and instrument vendors, professional societies, health systems, and blood donor centers. For more information, refer to the Extended Blood Product Genotyping Information Exchange white paper on Lantana’s website ( https://www.lantanagroup.com/wp-content/uploads/2021/08/Blood-Bank-Info-Exchange-White-Paper-1.pdf ). The blood product transfusion process requires evaluating both patient and donor red blood cell (RBC) phenotyping profiles to guide the selection of blood product units for compatibility and safety. There is consensus activity spearheaded by ISBT describing blood group phenotype-genotype correlations and nomenclature for determining patient-donor compatibility, but these consensus representations are currently insufficient for computational assessment and bidirectional data exchange between blood donor center Blood Establishment Computer Systems (BECS) and health systems’ Blood Bank Laboratory Information Systems (BBLIS). The lack of a digital interface between these information systems impairs the rapid identification of compatible donor units (especially in the case of a patient with an alloantibody), wastes rare resources by inadvertently releasing clinically important donor units for less significant conditions, and hinders full understanding of transfusion reactions, especially delayed transfusion reactions, due to a lack of detailed information on the blood groups involved in donor and patient transfusion. The development of a FHIR extended RBC phenotyping and genotyping implementation guide can accelerate and enhance both the patient's blood donor group description and the description of biologically-derived products. A standardized electronic information exchange may also support public reporting and safety measures associated with transfusions.